Phylogenetic interrelationships, taxonomy, and reductive evolution in ...

Zoological Journal of the Linnean Society, 2011, 163, 1096–1156. With 30 figures

Phylogenetic interrelationships, taxonomy, and reductive evolution in the Neotropical electric fish genus Hypopygus (Teleostei, Ostariophysi, Gymnotiformes) zoj_736

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CARLOS D. DE SANTANA† and WILLIAM G. R. CRAMPTON* University of Central Florida, Department of Biology, Orlando, FL, 32816-2368, USA Received 30 April 2010; accepted for publication 24 January 2011

A phylogenetic reconstruction of the Neotropical electric fish genus Hypopygus based on 47 parsimony-informative morphological characters is presented. A series of synapomorphies support the hypothesis of monophyly of Hypopygus, and partially resolve species-level relationships within the genus. Hypopygus species are recognized here as miniaturized fishes based on two criteria; first, a derived condition of diminutive body size, and; second, the presence of a suite of reductive morphological characters, including partial or total losses, simplifications, and reductions of the anal-fin rays, scales, cranial bones, and laterosensory canal system. Reductive characters associated with miniaturization comprise 45% of the total number of characters in the phylogenetic reconstruction of the genus. Miniaturization and reductive morphological evolution in Hypopygus are discussed here in the phylogenetic context. A taxonomic revision of Hypopygus is presented, in which five new species are described, two species previously assigned to the genus are redescribed, and a single known species of Stegostenopos is redescribed and included in Hypopygus as a junior synonym. Distribution maps and a key for all eight valid species of Hypopygus are provided, based on the examination of 5014 catalogued museum specimens. © 2011 The Linnean Society of London, Zoological Journal of the Linnean Society, 2011, 163, 1096–1156. doi: 10.1111/j.1096-3642.2011.00736.x

ADDITIONAL KEYWORDS: Amazon basin – Hypopomidae – miniaturization – Neotropics – Stegostenopos.

INTRODUCTION Miniaturization, a derived condition of diminutive body size in sexually mature animals in association with multiple reductive morphological characters, has evolved independently in several groups of vertebrates. Although miniaturization has been documented in amphibians and amniotes (e.g. Hanken & Wake, 1993), the phenomenon is most common in freshwater fishes, where numerous examples have been documented (e.g. Roberts, 1972; Whitehead & Teugels, 1985; Kottelat & Vidthayanon, 1993; Grande, 1994; Parenti, 2008; references for Neotropical examples below), including the

*Corresponding author. E-mail: [email protected] †Museu Paraense Emílio Goeldi, Av. Magalhães Barata 376, Cx. Postal 399, 66040-170 Belém, PA, Brazil.

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most extreme case in any vertebrate – the South-East Asian cyprinid Paedocypris progenetica, which matures at 7.9 mm standard length (Kottelat et al., 2006; Rüber et al., 2007; Britz & Conway, 2009). Reductive evolution in fishes commonly involves the derived loss of scales, fin rays, and elements of the laterosensory canal system, or the incomplete ossification or complete loss of skeletal bones, via paedomorphosis (e.g. Weitzman & Vari, 1988; Buckup, 1993; Hanken & Wake, 1993; Johnson & Brothers, 1993; Kottelat et al., 2006; Rüber et al., 2007). Many cases of miniaturization have been documented in Neotropical freshwater fishes, where the phenomenon is usually associated with access to the interstices of cluttered substrates (such as root masses, leaf litter, or gravel), and a diet comprising small aquatic invertebrates (e.g. Weitzman & Vari,

© 2011 The Linnean Society of London, Zoological Journal of the Linnean Society, 2011, 163, 1096–1156

HYPOPYGUS: PHYLOGENY AND TAXONOMIC REVISION 1988; Schaefer, Weitzman & Britski, 1989; Buckup, 1993; Weitzman & Malabarba, 1999; de Pinna & Winemiller, 2000; Britto, Lima & Santos, 2005; Rocha, de Oliveira & Rapp-Py Daniel, 2008; Bührnheim et al., 2008). Approximately 90% of known miniaturized Neotropical fishes belong to the ostariophysan orders Characiformes and Siluriformes (Weitzman & Vari, 1988; Schaefer et al., 1989; Buckup, 1993). Examples from other taxa include Fluviphylax (Cyprinodontiformes; Roberts, 1970; Costa & Le Bail, 1999) and Amazonsprattus (Clupeiformes; Roberts, 1984). However, cases of miniaturization have not yet been documented in any of the gymnotiforms, despite their diversity (currently 181 valid species), and abundance in a wide range of habitats. The electric knifefishes of the genus Hypopygus (currently placed in the Hypopomidae) are the smallest species in the order Gymnotiformes – exhibiting substantially reduced body size in comparison to immediate outgroups, and to all but a few other members of the order. They reach approximately 150 mm total length (TL) and 23.5 mm from snout to posterior end of body cavity (BC), and attain reproductive maturity at as little as 42 mm TL and 15.8 mm BC in one of the new species described here (Hypopygus minissimus). However, Hypopygus species exceed by nearly four times the maximum standard length of 26 mm suggested by Weitzman & Vari (1988) as a cut-off for identifying miniature fishes. Nonetheless, Weitzman & Vari (1988) acknowledged that this cut-off point is arbitrary, and especially unsatisfactory when applied to species with elongated bodies. Hypopygus, like other gymnotiforms, exhibit an extremely elongated body – manifest as an extension of the portion of the body posterior to the coelomic cavity. Most structures posterior to the coelomic cavity are specializations for the combined electrogenic and electrosensory system: i.e. (1) the bulk of the hypaxial electric organ and support structures; (2) an array of electroreceptors on the body surface, and; (3) most of the elongated anal-fin and its support structures – which permit both the retention of a rigid posture during movement, and also the ability to ‘scan’ objects with back and forth probing movements – both important requisites of efficient active electroreception (reviews in Moller, 1995; Albert & Crampton, 2005; Bullock et al., 2005). We have noted that a measure of body length that excludes these specialized portions of the body posterior to the coleomic cavity should place all species of Hypopygus firmly within the limits of most miniaturized fishes. For instance, a standard length of 26 mm for a generalized characiform fish (e.g. a typical Hyphessobrycon) is equivalent to a length from snout to the end of the BC of approximately 20 mm. Most

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species of Hypopygus mature below 20 mm BC, and typically do not exceed this length at their maximum known size. Hence, on grounds of size alone, we propose that Hypopygus species may qualify as cases of miniaturization. Moreover, we will also note that many reductive morphological characters are present in the genus. Species of the genus Hypopygus are known from the Amazon and Orinoco basins, major drainages of the Guianas, and parts of the northern Paraguay basin, but are unknown from trans-Andean South America, and from coastal drainages of north-eastern and southern Brazil (Nijssen & Isbrücker, 1972; Albert & Crampton, 2003; Crampton, 2011). Hypopygus are a common component of the nocturnally active fauna of streams, small tributaries, and floodplains of low conductivity river systems where they occur in and around submerged leaf litter, roots, and aquatic vegetation (Heiligenberg & Bastian, 1980; Alves-Gomes, 1997; Crampton, 1998). Hypopygus lepturus Hoedeman have been reported to hide during the day in the substrate – where they are typically found in groups of up to several dozen specimens, spaced less than 10 cm from each other (Hopkins & Heiligenberg, 1978; Henderson & Walker, 1990; Alves-Gomes, 1997). Most of the known species present cryptic or disruptive pigmentation, which can be hard to distinguish from a background of submerged leaves. Some species of Hypopygus may qualify as leaf-mimicking fishes, of which several have been documented in the Amazon, including the closely related Steatogenys duidae (Sazima et al., 2006). Hypopygus are known to feed on small autochthonous and allochthonous invertebrates (Goulding, Carvalho & Ferreira, 1988; Lima et al., 2005; Ferreira et al., 2007). The reproductive ecology of Hypopygus is largely unknown, although Lima et al. (2005) reported oviposition on the surface of leaves and roots in two species. Hypopygus are especially common in lowland rainforest and savannah streams, where they may form a significant component of food webs. However, they are of negligible food value to humans. Lima et al. (2005) reported taboos against the consumption of Hypopygus by the Tukano and Tuyuka tribes of the Brazilian Amazon; the name for Hypopygus and species of Brachyhypopomus, meperõ kamikuagu, means ‘twisting, worm-like creature that provokes skin lesions’. Chao (2001) included Hypopygus in lists of ornamental fishes exported from the middle Rio Negro but the genus does not appear commonly in the export trade. Like all Gymnotiformes, Hypopygus generate electric organ discharges (EODs), which, in combination with an array of electroreceptors, permit the detection of objects in the dark (i.e. electrolocation) and also electric communication (Heiligenberg, 1974; Bullock et al., 2005). The EODs comprise short (c. 0.8–2 ms),


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pulsed, multiphasic waveforms generated at varying rates, from approximately 30 to 100 Hz (Hopkins, 1974; Schwassmann, 1978; Kramer, Kirschbaum & Markl, 1981; Crampton, 1998; Crampton & Albert, 2006). The EOD of H. lepturus comprises four phases of alternating polarity. It begins with a weak negative phase (P0 sensu Crampton & Albert, 2006), followed by a strong biphasic component (P1, P2), and finally a weak positive phase (P3) (Hopkins, 1974: fig. 5; Hopkins & Heiligenberg, 1978: fig. 1; Heiligenberg & Bastian, 1980: fig. 2; Crampton & Albert, 2006: fig. 24.8). Hypopygus ortegai sp. nov. is also known to generate a similar, tetraphasic EOD (Crampton & Albert, 2006, 672, fig. 24.8, mistakenly identified as Stegostenopos cryptogenes). The EOD pulse rate typically increases from a resting day-time rate to a higher nocturnal rate, corresponding to foraging activity (Hopkins, 1974; Schwassmann, 1978; Crampton, 1998). Hypopygus respond to conspecific EODs generated at a similar pulse rate with a jamming avoidance response (JAR), involving a shift in EOD rate to avoid coincident pulses (Heiligenberg, 1974). Hypopygus was in fact used as a model taxon in the first documentation of the JAR in pulse-type gymnotiforms (Heiligenberg, 1974). Hoedeman (1962) established the genus Hypopygus, describing H. lepturus from the Marowijne River drainage in Suriname. Later, Mago-Leccia (1994) described Hypopygus neblinae from the Río Baría drainage in Venezuela. Only these two species have to date been described. The phylogenetic position of Hypopygus has been discussed by several authors (Mago-Leccia, 1978; Triques, 1993; Alves-Gomes et al., 1995; Albert & Campos-da-Paz, 1998; Albert, 2001). Mago-Leccia (1978) placed Hypopygus within the family Hypopomidae, a scheme also followed by Mago-Leccia (1994), Albert & Campos-da-Paz (1998), Albert (2001), and Albert & Crampton (2003). Within the Hypopomidae, Triques (1993), Alves-Gomes et al. (1995), Albert & Campos-da-Paz (1998), and Albert (2001) placed Hypopygus as the sister taxon to Steatogenys. Albert (2001) erected the tribe Steatogenini (originally misspelled as ‘Steatogeni’ but later corrected by Crampton, Thorsen & Albert, 2004) to encompass Hypopygus and Steatogenys. Based largely on osteological and other morphological characters, Albert (2001) placed Steatogenini in a polytomy with Brachyhypopomus and the Microsternarchini (Microsternarchus and Racenisia). This polytomy was placed as sister taxon to the monotypic genus Hypopomus. The position of the Steatogenini has nonetheless been disputed: Alves-Gomes et al. (1995) used mitochondrial DNA sequence data and additional electrophysiological characters to place Steatogenini as sister taxon to Gymnorhamphichthys

and Rhamphichthys in the family Rhamphichthyidae (which now also includes Iracema, Triques, 1996). Triques (1997) erected the genus Stegostenopos, based on the description of a single species, Stegostenopos cryptogenes, from the Rio Cuieiras in the lower Rio Negro basin, Brazil. He also provided evidence of a sister relationship between the genera Stegostenopos and Hypopygus, placing these two genera as sister taxon to Steatogenys. Albert (2001) assigned Steg. cryptogenes to Steatogenys without discussion but later, in Albert & Crampton (2003), listed Stegostenopos as a valid genus. Herein we will demonstrate that Stegostenopos belongs unambiguously to Hypopygus. The specific aims of this paper are: (1) determine the monophyly and limits of the genus Hypopygus based on cladistic analysis of external and internal morphology, with a revaluation of the status of Stegostenopos; (2) present a phylogenetic hypothesis of species-level interrelationships in Hypopygus; (3) explore the hypothesis that Hypopygus species are miniaturized fishes, and evaluate if reduced body size in Hypopygus is associated with reductive morphological characters sensu Weitzman & Vari (1988), and; (4) present a comprehensive taxonomic revision of Hypopygus, with the description of five new species, the redescription of existing species, and the presentation of a dichotomous identification key as well as distribution maps based on the examination of 5014 catalogued museum specimens.

MATERIAL AND METHODS MORPHOMETRICS

AND MERISTICS

Measurements Body size measurements reported in this paper refer to TL unless otherwise stated. Morphological abbreviations used commonly in the text are reported below in parentheses. Morphological measurements were taken as point-to-point linear distances, utilizing digital callipers, to 0.1 mm. Measurements were as follows: anal-fin length – the distance between the bases of the first and last rays of the anal fin; anus to anal-fin base – the distance from the posterior margin of the anus to the first ray of the anal fin; body depth at anal-fin origin – body depth measured from dorsal midline to ventral midline at the anal-fin origin; body width at anal-fin origin – the maximum body width at anal fin origin; caudal filament depth – the depth of the caudal filament measured at the base of the last anal-fin ray; caudal filament length – the distance from the base of the last anal-fin ray to the tip of the caudal filament; head depth at eye – the maximum head depth measured at the centre of the eye; head width at eye – the maximum head width measured at


HYPOPYGUS: PHYLOGENY AND TAXONOMIC REVISION the centre of the eye; head length (HL)– the distance from the tip of the snout to the posterodorsal angle of the branchial opening; interocular width – the minimum width between the dorsal margins of the orbits; length to end of anal-fin (LEA) – the distance from the tip of the snout to the base of the last anal fin; pectoral-fin length – the distance between the base of the dorsal-most ray of the pectoral fin and the distal-most point on the margin of the fin; orbital diameter – the horizontal width of the eye; postorbital length – distance from the posterior margin of the eye to the posterodorsal angle of the branchial opening; snout length – the distance from the tip of the snout to the anterior margin of the eye; snout to occiput – the distance from the tip of the snout to the occiput; snout to end of BC – the distance from the tip of the snout to the posterior extremity of BC; and TL, distance from the tip of the snout to the end of the tip of the caudal filament. Counts Vertebrae were counted from radiographs or cleared and stained specimens. Counts of anal- and pectoralfin rays were taken under a stereomicroscope with backlight illumination. Scales below the lateral line were counted diagonally from below the lateral line to the dorsal extremity of the anal-fin pterygiophores.

MATERIAL

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Natural History Survey, Champaign, IL; INPA, Instituto Nacional de Pesquisas da Amazônia, Manaus, Brazil; MBUCV-V, Museo de Biología de la Universidad Central de Venezuela, Caracas, Venezuela; MCNG, Museum de Ciencias Naturales, Guanare, Venezuela; MCP, Museu de Ciências e Tecnologia, Pontificia Universidade Católica do Rio Grande do Sul, Porto Alegre, Brazil; MCZ, Museum of Comparative Zoology, Harvard University, Cambridge, MA; MNHN, Muséum National d’Histoire Naturelle, Paris, France; MNRJ, Museu Nacional, Rio de Janeiro, Brazil; MPEG, Museu Paraense Emílio Goeldi, Belém, Brazil; MPUJ, Museo de la Pontificia Universidad Javeriana, Bogotá, Colombia; MUSM, Museo de Historia Natural de la Universidad Nacional Mayor de San Marcos, Lima, Peru; MZUSP, Museu de Zoologia da Universidade de São Paulo, Brazil; NRM, Swedish Museum of Natural History, Stockholm, Sweden; RMNH, Rijksmuseum van Natuurlijke Historie, Leiden, Netherlands; ROM, Royal Ontario Museum, Toronto, Canada; UF, Florida Museum of Natural History, Gainesville, FL; UFRO-I, Universidade Federal de Rondônia, Porto Velho, Brazil; UMMZ, Museum of Zoology, University of Michigan, Ann Arbor; MI; UMSS, Universidad Mayor de San Simón, Cochabamba, Bolivia; USNM, National Museum of Natural History, Smithsonian Institution, Washington D.C.; ZMA, Zoologisch Museum, Universiteit van Amsterdam, Netherlands.

EXAMINED

Material examined is ordered alphabetically by country (in capital letters), state or department (in italics), and collection institution, and then numerically by collection lot number. Geographical coordinates are given only where available. Lots without exact localities are excluded from the spot-maps. All body sizes (given in mm) refer to TL. Cleared and stained specimens are marked CS. Field numbers beginning with the letters WC refer to specimens with EODs recorded by the second author. The last six digits refer to the day, month, and year (e.g. 150304 = 15 March 2004) and the first two digits to a unique recording number. Abbreviations for collection institutions are: AMNH, American Museum of Natural History, New York, NY; ANSP, Academy of Natural Sciences of Philadelphia, Philadelphia, PA; AUM, Auburn University Museum, Auburn, AL; BMNH, The Natural History Museum, London, UK (formerly British Museum, Natural History); CASSU, California Academy of Sciences, San Francisco, CA (former Stanford University collections); CBF Colección Boliviana de Fauna, La Paz, Bolivia; CU, Cornell University, Ithaca, NY; FMNH, Field Museum of Natural History, Chicago, IL; IAVHP, Instituto de Investigacíon de Recursos Biológicos Alexander von Humboldt, Villa de Leyva, Colombia; INHS, Illinois

OSTEOLOGICAL

PREPARATION AND NOMENCLATURE

Species were cleared and counterstained (CS) for cartilage and bone using the method outlined by Taylor & Van Dyke (1985). In some specimens with weak ossification, bones were stained with alizarin red in ethanol solution instead of KOH alizarin solution (Springer & Johnson, 2000). The pectoral girdle, suspensorium, and components of the head were removed following the procedures summarized by Weitzman (1974). Osteological nomenclature and homology follow de Santana & Vari (2010) and Hilton et al. (2007), except for lateral line system nomenclature, which follows Arratia & Huaquin (1995).

ILLUSTRATIONS Drawings were carried out with aid of a camera lucida attached to a Meiji Techno RZ stereomicroscope. The final art was rendered from scanned drawings using a Wacom Bamboo electronic tablet, and then edited in Adobe Illustrator and Adobe Photoshop. Some illustrations were prepared from the right side of dissected specimens and are inverted left-toright to place the anterior portion of the morphology


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in the traditional left position. Inverted figures are noted in the figure captions. All body and head photographs were taken on a light stand using a Nikon D-200 digital camera and a Nikon Micro-Nikkor 55 mm lens. Images of live specimens in aquaria were taken with a Nikon Coolpix 5000 digital camera. All images of cleared and stained specimens were taken on an illuminated light table using a Nikon Coolpix P5100 digital camera attached to a Nikon EZ-Micro field microscope, at a fixed magnification of 20 ¥.

ELECTRIC

SIGNAL RECORDINGS

Here we provide only brief notes on EOD waveform and pulse rate. A more detailed study of intraspecific and interspecific signal diversity in the Steatogenini will be published elsewhere. Electric signals were recorded using the procedure summarized in Crampton et al. (2008). In brief, fishes were recorded in a nylon-mesh envelope suspended in the centre of a 120 L cooler containing water from the capture locality. Temperature was standardized to 27.0 ± 0.2 °C for at least 5 min before recording. Signals were amplified from tank-end silver-silver chloride or nickelchromium electrodes using an AC-coupled amplifier (DC or 0.01 Hz–50 kHz; custom built following Wells & Crampton, 2006; CWE BMA 200; or Ametek SR-5113) and digitized at 48–200 kHz (Sony TCD D3 or D7 DAT recorder; Edirol UA-5; or National Instruments DAQ-6052E). All EODs were saved as ASCII files for analysis in custom written MATLAB (The MathWorks, Natick, MA) or JAVA (Sun Microsystems, Inc., Santa Clara, CA) programs. EOD duration was measured at the first and last sample to exceed 1% of peak-to-peak voltage. EOD peak power frequency was computed from a 65536-point fast Fourier transform. EOD pulse rate was measured from fish held at 27.0 ± 0.5 °C in separate buckets or tanks, under subdued natural light regimes, and characterized from 1-min recordings. Fishes with damage to the caudal appendage, even if subsequently regenerated, were excluded from analysis.

FRAMEWORK

FOR OUTGROUP COMPARISONS

AND NOMENCLATURE

We define the ingroup as Hypopygus and Stegostenopos, although we will demonstrate that the single known species of Stegostenopos must be assigned to Hypopygus. For the purpose of phylogenetic analysis Steatogenys (based on Stea. duidae) was used as the proximate outgroup to Hypopygus and Stegostenopos, following the hypothesis proposed by Triques (1993), and subsequently corroborated by Alves-Gomes et al. (1995), Triques (1997), Albert & Campos-da-Paz (1998), and Albert (2001).

The position of the tribe Steatogenini ((Hypopygus, Stegostenopos) Steatogenys) within the gymnotiforms is, however, disputed (i.e. as a member of Hypopomidae, e.g. Albert, 2001, versus as a member of Rhamphichthyidae, e.g. Alves-Gomes et al., 1995). The Steatogenini was considered to belong to Hypopomidae by Mago-Leccia (1978), Mago-Leccia (1994), and Albert (2001). Conversely, Alves-Gomes et al. (1995), based on molecular, electrophysiological, and morphological data, argued that Steatogenini is more closely related to Gymnorhamphichthys and Rhamphichthys (Rhamphichthyidae) than to Brachyhypopomus and Microsternarchus (Hypopomidae). Our on-going (unpublished) morphological and molecular studies of species and genus-level relationships within the Rhamphichthyoidea [Hypopomidae (including Steatogenini), and Rhamphichthyidae] corroborate Alves-Gomes et al.’s (1995) placement of the Steatogenini as sister group to the Rhamphichthyidae. We therefore define our secondary outgroup as Gymnorhamphichthys and Rhamphichthys. In so doing we recognize the necessity for a revision of the genus-level relationships within the Rhamphichthyoidea, and make an advanced assumption that the Steatogenini will in due course be moved into the Rhamphichthyidae as recommended by Alves-Gomes et al. (1995). Such a higher-level revision is beyond the scope of this paper. Instead we restrict our analyses of synapomorphic characters to the ingroup Hypopygus and Stegostenopos. For clarity, we refer to the proximate outgroup (Steatogenys – Stea. duidae) and secondary outgroups (Gymnorhamphichthys – Gymnorhamphichthys rondoni; and Rhamphichthys – Rhamphichthys marmoratus) together as the ‘immediate outgroups’, to distinguish these from more distantly related genera. Nonetheless, to test the efficacies of outgroup comparison we performed a separated analysis including members of the genera Brachyhypopomus (Brachyhypopomus brevirostris), Hypopomus (Hypopomus artedi), and Microsternarchus (Microsternarchus bilineatus) as additional secondary outgroups. No specimens of the genus Iracema (which strongly resembles Gymnorhamphichthys) were available for clearing and staining in the present study, or in any previous studies (e.g. Albert, 2001). Consequently, we relied upon the original description of Iracema (Triques, 1996) in formulating our generic diagnoses of Hypopygus. Owing to the absence of osteological information in the original description, we opted to exclude Iracema from our phylogenetic matrix (Appendix 1). To summarize, our ingroups and outgroups are defined as: Ingroup: Hypopygus (seven species) and Stegostenopos cryptogenes.


HYPOPYGUS: PHYLOGENY AND TAXONOMIC REVISION Immediate outgroups Proximate outgroup: Steatogenys (based on Stea. duidae) Secondary outgroup: Rhamphichthyidae (based on Gymnorhamphichthys rondoni and R. marmoratus). Additional secondary outgroup: Hypopominae (based on B. brevirostris, Hypopomus artedi, and M. bilineatus).

PHYLOGENETIC

METHODS

Hypotheses of phylogenetic relationships are based on the cladistic tenets proposed by Hennig (1966) and subsequently elaborated by a series of authors (e.g. Nelson & Platnick, 1981; Wiley, 1981; Wiley et al., 1991; Forey et al., 1996; Kitching et al., 1998). The search method best supported by the integrated data was Wagner parsimony, under which character reversals and convergences are permissible and quantified equally (Swofford & Maddison, 1987). The analysis was carried out using PAUP* 4.0B10 (Swofford, 2003). A parallel analysis was undertaken in NONA (Goloboff, 1999) in its shell WINCLADA (Nixon, 1999– 2002). The matrix of 47 characters and 11 terminal taxa was built in MacClade (Maddison & Maddison, 2005). Tree manipulations and character diagnoses were also executed in MacClade. All characters were divided into two character states, except those numbered 18 and 43, which were defined as multistate characters. Outgroup comparisons served as the basis for character polarity inferences, following the methodology proposed by Nixon & Carpenter (1993). Characters were coded as unordered in the analysis of the data matrix. The definition of reductive characters follows Weitzman & S. Fink (1985: 10): ‘. . . those associated with a loss or reduction of some particular structure present in outgroups’. Reductive characters are indicated as evolutionary novelties in the section ‘Character description and analysis’. Rooting was made a posteriori at the proximate outgroup clade formed by Steatogenys, which is hypothesized as the sister group to Hypopygus (Alves-Gomes et al., 1995; Albert & Campos-da-Paz, 1998; Albert, 2001). Ambiguous character distributions were resolved using ACCTRAN ‘accelerated transformation optimization’ (Farris optimization), which maximizes reversals over parallelism (de Pinna, 1991). Decay indices, also known as Bremer support (Bremer, 1988, 1994), were calculated in PAUP* via a script generated in TreeRot v.2c (Sorenson, 1999) using the final tree topology obtained in PAUP*.

RESULTS PHYLOGENETIC RECONSTRUCTION Forty-seven characters that vary within Hypopygus or that diagnose the genus as monophyletic were

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compiled from examination of the cleared and stained specimens listed in Appendix 2 (see below under ‘Character description and analysis’) and from the whole specimens listed under taxonomic accounts. A branch and bound exact-solution algorithm search was undertaken with the following options: stepwise addition, minimal trees only, and furthest addition sequence. A search was performed in PAUP*, and included Gymnorhamphichthys, Rhamphichthys, and Steatogenys as outgroups, with branches of zero maximum length collapsed. This yielded one most parsimonious tree with a length of 54, consistency index (CI) = 0.907, and retention index (RI) = 0.928. The analysis of interrelationships using a minimum tree length of zero also resulted in a single tree, with identical topology and scores. A parallel analysis in NONA (Goloboff, 1999), in its shell WINCLADA (Nixon, 1999–2002), using the same conditions as in PAUP* and a search strategy of Mult* yielded one tree with the same topology as in the PAUP* analysis, with a length of 53, CI = 0.900, and RI = 0.920. The final tree topology represents the results of analysis from PAUP* with all characters unordered (Fig. 1). An additional branch and bound search was undertaken by adding Brachyhypopomus, Hypopomus, and Microsternarchus as additional immediate outgroups. This analysis resulted in a single most parsimonious tree with the same topology as the previous analysis (i.e. the topology presented in Fig. 1), a length of 65, CI = 0.754, and RI = 0.868. The addition of these three outgroup taxa therefore increased the frequency of homoplasy (CI = 0.754 versus 0.907), and decreased the frequency of synapomorphy (RI = 0.868 versus 0.928). The inclusion of these three taxa also affected two otherwise unambiguous putative synapomorphies for Hypopygus: character 22, the loss of the vomer; and character 45, the presence of an opaque tissue covering the base of the anal fin. The loss of the vomer in the Hypopygus clade ‘A’ (see Fig. 1), is, presumably a reduction associated with miniaturization (see Discussion). In contrast, the nature of the absence of the vomer in Brachyhypopomus, Hypopomus, and Microsternarchus and in all other members of Hypopomidae is unknown, as most of the species belonging to these genera show no signs of being miniaturized. Therefore, we consider the absence of the vomer in Hypopygus and Hypopomidae to be nonhomologous. The presence of an opaque tissue covering the base of the anal fin in Hypopygus, in Steatogenys, and in the Hypopominae (Hypopomus, Brachyhypopomus, and Microsternarchini) was used by Mago-Leccia (1994) as a synapomorphy to place Hypopygus in Hypopomidae. This tissue is present only in alcohol preserved specimens of Hypopygus


42 26 16 4 31R 28

41 38 21 9

Hypopygus ortegai

Hypopygus nijsseni

Hypopygus minissimus

Hypopygus hoedemani

Hypopygus lepturus

Hypopygus cryptogenes

Hypopygus isbruckeri


Hypopygus neblinae

Immediate outgroups

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44 6

25 Clade 7 F 3

39 33 Clade E 15 37 8

36

35

Our results corroborate the monophyly of Hypopygus suggested by Nijssen & Isbrücker (1972), MagoLeccia (1994), Triques (1997), Albert & Campos-daPaz (1998), and Albert (2001). Together these studies employed a total of 33 putative apomorphic or synapomorphic characters to define Hypopygus (Table 1). However, only six of 33 previously proposed genericlevel synapomorphies are corroborated in this study (see ‘Unutilized characters’). In addition, we found that five characters previously described as synapomorphies for Hypopygus were in fact not synapomorphies, but instead informative of interspecific relationships within Hypopygus and Stegostenopos (see Character description and analysis; and Synapomorphy scheme, below).

5 Clade D

19 Clade C 31 46 43 22 14 2

23 Clade B

47 45 29 17 13 1 Clade A

Figure 1. Single most parsimonious phylogenetic tree for Hypopygus, showing the distribution of unambiguous character state transformations. Black rectangles represent reductive characters, and grey rectangles nonreductive characters, with numbers corresponding to character descriptions in the text. Characters marked with the suffix ‘R’ indicate a reversal of character state. Characters 10–12, 20, 24, 27, 30, and 40 are excluded because they evolve outside clade A. The tree was generated in PAUP* based on the matrix in Appendix 1, rooted a posteriori in the proximate outgroup Steatogenys, and optimized with accelerated transformation optimization (ACCTRAN). Immediate outgroups correspond to Steatogenys (proximate outgroup) and Gymnorhamphichthys + Rhamphichthys (secondary outgroups). Characters 18 and 43 were defined as multistate. Tree length = 54, consistency index = 0.907, and retention index = 0.928, with all branches of zero maximum length collapsed and all characters unordered.

but in both alcohol and cleared and stained specimens of Hypopominae. This discrepancy may be indicative of structural differences in these tissues and here we regard this tissue as nonhomologous between the Steatogenini (Hypopygus and Steatogenys) and Hypopominae.

CHARACTER DESCRIPTION AND ANALYSIS The following discussion is arranged by discrete body systems and ordered in an approximately anterior to posterior sequence. Characters involving multiple portions of an individual (e.g. pigmentation) are presented last. In each case, a brief description of the character is followed by summaries of the alternative character states, the consistency and retention indices under the final phylogenetic hypothesis (Fig. 1), and finally a discussion of the distribution of character states amongst the ingroup and outgroup species. Additional comments on the characters are included where appropriate.

NARES 1. Position of anterior nares: (0) outside upper lip; (1) inside upper lip (CI = 1.000; RI = 1.000). In Steatogenys, Gymnorhamphichthys, and Rhamphichthys the anterior nares are positioned near the tip of the snout, outside the upper lip (state 0; Triques, 1997: 3, fig. 4; Crampton et al., 2004: 83, fig. 3). As first noted by Mago-Leccia (1994: 50), the anterior nares are located inside the upper lip in all species of Hypopygus and in Stegostenopos cryptogenes (state 1; Hoedeman, 1962: 99, fig. 4b; Triques, 1997: 3, fig. 3). Consequently, Triques’s (1997) hypothesis of the position of the anterior nares as a synapomorphy for Hypopygus and Steg. cryptogenes is corroborated here. 2. Presence or absence of posterior nares: (0) present; (1) absent (CI = 1.000; RI = 1.000). The posterior nares are present in the immediate outgroups, as well as in most other gymnotiform species (state 0) (e.g. Steatogenys, Crampton et al., 2004: 83, fig. 3; Rhamphichthys, Mago-Leccia, 1994: 162, fig. 61). The posterior nares are absent (state 1)


HYPOPYGUS: PHYLOGENY AND TAXONOMIC REVISION

1103

Table 1. List of apomorphies and synapomorphies historically used to define Hypopygus Character/author Small body size (U1) Lateral line incomplete (46) Roundish snout (U2) Postpectoral accessory electric organ (47) Urogenital papilla well developed (U3) Anterior and posterior nares remote (U4) Anterior nares inside the upper lip (1) Absence of posterior nares (2) Premaxilla small, laminar, and conical (U5) Absence of teeth (U6) Mesethmoid short (U7) Absence of vomer (22) Endopterygoid elongate with ascending process(U8) Absence of lateral ethmoid (U9) Infraorbital series reduced to first and sixth Cranial fontanels well developed Supraorbital canal partially free from frontal bone Post-temporal separate from supracleithrum (29) Absence of mesocoracoid Coracoid without ventral process Four pectoral radials (U10) Pectoral radials third and fourth separate (U11) Uruhyal enlarged (U12) Four branchiostegal rays Gill rakers as three to four fleshy lobes (U13) Basihyal short, shovel-like (U14) Two ossified basibranchials Posterior process of fifth epibranchial short (U15) Seventh epibranchial with posterior process (U16) Three ossified infrapharyngobranchials (U17) First infrapharyngobranchial unossified (U18) Precaudal vertebrae 13–14 (U19) Body cavity short, 11 or fewer precaudal vertebrae (U20)

1

2

3

4

5

X

X

X

X X

6

X X X

X X X X

X X

X

X X

X X X

X X X X X X X X X X X X

X

X

X X X X X

X

X

X

X

X

X X

X X X X

1, Nijssen & Isbrücker 1972; 2, Mago-Leccia 1994; 3, Triques 1997; 4, Albert & Campos-da-Paz 1998; 5, Albert 2001; and 6, present study. Numbers in parentheses refer to characters in Character description and analysis. U, unutilized characters.

in all ingroup species, constituting a synapomorphy for Hypopygus and Stegostenopos, as observed by Triques (1993, 1997; figs 1, 2). Mago-Leccia (1994: 50), mistakenly suggested the presence of posterior nares in Hypopygus. The confusion may stem from an illustration of H. lepturus in Hoedeman (1962: 99, fig. 4a), in which a small aperture near to the anterior border of the eye could be mistaken for a posterior naris, but is in fact a sensory canal pore. The loss of the posterior nares is interpreted here as an evolutionary novelty in the ingroup and may be associated with changes to the olfactory organ and its function.

NASAL

LATEROSENSORY CANAL

3. Presence or absence of nasal laterosensory canal: (0) present; (1) absent (CI = 1.000; RI = 1.000). The nasal laterosensory canal is present in most species of Hypopygus, in Steg. cryptogenes, and in all the immediate outgroups as tube-like ossicles or as soft tissue (state 0; Figs 2, 3). It is present, as a soft tissue structure, in juveniles of H. lepturus (c. 30.0–46.5 mm; Appendix 3). In contrast to most species of Hypopygus, the nasal laterosensory canal is lost in Hypopygus hoedemani and H. minissimus (state 1; Fig. 4).


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pac pasoc

esc pocl

soc nc

ptoc aoc

ioc 4-6 ioc 1-3

mc 1-3 mc 4-5 poc

Figure 2. Cleared and stained head of juvenile Brachyhypopomus sp. indet, MCP uncatalogued, 74 mm; left side, lateral view, anterior to left. Upper image shows unmanipulated digital photograph. Lower image is presented as a ‘negative’, for contrast, with cephalic sensory canal elements highlighted (red) and labeled, and the outline of an unidentified bone, located underneath the antorbital, highlighted (yellow), with no labels. Some of the elements highlighted (red and yellow) are outside the focal plane of the upper image. Abbreviations: aoc, antorbital canal; esc, extrascapular; ioc, infraorbital canal; mc, mandibular canal; nc, nasal laterosensory canal; pac, parietal canal; pasoc, parietal branch of supraorbital canal; poc, preopercular canal; pocl, postotic canal of the lateral line; ptoc, pterotic canal; soc, supraorbital canal. See Zoological Journal of the Linnean Society online for the colour version of this Figure.

UPPER

JAW

4. Form of descending process of maxilla: (0) narrow; (1) broad (CI = 1.000; RI = 1.000). The descending process of maxilla is narrow; distinctly narrower than an unidentified bone embedded in the snout (see ‘Supraorbital, infraorbitals, and associated structures’, below), without a posterior ossified layer, in

Steg. cryptogenes, in Steatogenys, and in most of the secondary outgroups (state 0; Fig. 5A). It is broad; approximately the same width or wider than the putatively novel bone embedded in the snout, with a posterior ossified layer, in H. hoedemani and H. minissimus (state 1; Fig. 5B). A broad maxilla also occurs in the distantly related Microsternarchini (Mago-Leccia, 1994: 175, fig. 77).



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esc soc pac

pocl

nc uib

ptoc

io6

dpoc

mc 1-3 mc 4-5 vpoc

Figure 3. Head of adult Hypopygus ortegai, UF 176879, 101 mm; left side, lateral view, anterior to left. Cephalic sensory canal elements, and the outline of an unidentified bone (located under the antorbital), are highlighted grey. Abbreviations: dpoc, dorsal branch of the preopercular canal; esc, extrascapular canal; io, infraorbital canal; mc, mandibular canal; nc, nasal laterosensory canal; pac, parietal canal; pocl, postotic canal of the lateral line; ptoc, pterotic canal; soc, supraorbital canal; uib, unidentified bone; vpoc, ventral branch of the preopercular canal.

esc

soc ptoc uib

mc 1

A Figure 4. Head of adult Hypopygus minissimus, UF 148533 (WC 41.120304), female, 43 mm; left side, lateral view, anterior to left. Cephalic sensory canal elements, and the outline of an unidentified bone (located under the antorbital), are highlighted grey. Abbreviations: esc, extrascapular canal; mc, mandibular canal; ptoc, pterotic canal; soc, supraorbital canal; uib, unidentified bone.

B

Figure 5. Maxilla of: A, Steatogenys duidae MCP 31952 (WC14.240899), immature, 122 mm; anterior to left, inverted figure. B, Hypopygus minissimus UF 148533 (WC41.120304), female, 43 mm; left side, lateral view; larger stippling represents cartilage, anterior to left.


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C. D. DE SANTANA and W. G. R. CRAMPTON posterodorsal margin of dentary anguloarticular

dentary

coronomeckelian bone

Meckel’s cartilage retroarticular posterior process of dentary

Figure 6. Lower jaw of Hypopygus isbruckeri, UF 148539, 90 mm; left side, medial view, anterior to left. Note the posterodorsal margin of the dentary is straight. posterodorsal margin of dentary anguloarticular

coronomeckelian bone

dentary

Meckel’s cartilage

posterior process of dentary

retroarticular

Figure 7. Lower jaw of Hypopygus cryptogenes, MZUSP 30088, 147 mm; left side, medial view, anterior to left. Note the posterodorsal margin of the dentary is concave.

LOWER

JAW

5. Form of posterodorsal margin of dentary: (0) straight or irregular; (1) concave (CI = 1.000; RI = 1.000). The posterodorsal margin of the dentary is straight or irregular in most species of Hypopygus, and in Steatogenys, Gymnorhamphichthys, and Rhamphichthys (state 0; Fig. 6). It is concave in H. hoedemani,

H. minissimus, and Steg. cryptogenes (state 1; Fig. 7). The posterodorsal margin of the dentary is polymorphic (i.e. irregular or concave) in H. lepturus, and concave in the distantly related Microsternarchini Mago-Leccia 1994: 175, fig. 77). 6. Presence or absence of second mandibular canal bone: (0) present; (1) absent (CI = 1.000; RI = 0.000).


HYPOPYGUS: PHYLOGENY AND TAXONOMIC REVISION Five independently ossified mandibular canal bones are present in adults of the immediate outgroups, in most species of Hypopygus, and in Steg. cryptogenes (state 0; Fig. 3). Five unossifed mandibular canal bones are present in juveniles of all available examined immediate outgroups and most Hypopygus species (c. 23.3–122.0 mm; Appendix 3). In adults of H. minissimus only the first (anterior-most) mandibular canal bone is present (Fig. 4). Two anterior canal bones are present in H. hoedemani and three are present in H. lepturus. Therefore, the absence of the second mandibular canal bone is an autapomorphy for H. minissimus (state 1; Fig. 4). 7. Presence or absence of third mandibular canal bone: (0) present; (1) absent (CI = 1.000; RI = 1.000). The third mandibular canal bone is present in all immediate outgroup members, in most species of Hypopygus, and in Steg. cryptogenes (state 0; Figs 2, 3). The third mandibular canal bone is lost in H. hoedemani and H. minissimus (state 1; Fig. 4; Appendix 3). 8. Presence or absence of fourth mandibular canal bone: (0) present; (1) absent (CI = 1.000; RI = 1.000). The fourth mandibular canal bone is present in all immediate outgroup members, in most species of Hypopygus, and in Steg. cryptogenes (state 0; Figs 2– 3). It is lost in H. hoedemani, H. lepturus, and H. minissimus (state 1; Fig. 4; Appendix 3). 9. Presence or absence of fifth mandibular canal bone: (0) present; (1) absent (CI = 1.000; RI = 1.000). The fifth mandibular canal bone is present in all immediate outgroup members, in most species of Hypopygus, and in Steg. cryptogenes (state 0; Figs 2– 3). It is lost in H. hoedemani, H. lepturus, and H. minissimus (state 1; Fig. 4; Appendix 3).

SUPRAORBITAL

AND INFRAORBITAL SERIES AND

ASSOCIATED STRUCTURES

In basal members of the Siluriformes and in the Gymnotiformes, the antorbital and infraorbital series (usually six infraorbital series) are typically represented by ossified or collagenous canal-bearing elements associated with the lateralis sensory system (Fink & Fink, 1981: 316, fig. 7; Arratia, 1987: figs 13, 22; Arratia & Huaquin, 1995: fig. 6). Enlarged, ossified antorbital bones and first to fourth infraorbital bones associated with sensory canals are present in the Characiformes (Weitzman, 1962: figs 64–65; Sidlauskas & Vari, 2008: figs 8–13) and some taxa in the Gymnotiformes, e.g. Rhabdolichops (Mago-Leccia,

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1978: 57, fig. 9; Lundberg & Mago-Leccia, 1986: 56, fig. 2) and Sternopygus (de La Hoz & Chardon, 1984: 2, fig. 4). In addition to possessing the antorbital and all six infraorbital canal-bearing elements associated with the cephalic lateralis sensory system (except where they exhibit derived loss; Figs 2–4), we noted that rhamphichthyoid taxa also possess a paired, immobile bone without a sensory canal (labelled ‘unidentified bone’ in Figs 2–4), the identity and homology of which has not been adequately documented. This bone is embedded in the tissue of the snout, located dorsal to the maxilla and ventral to the antorbital bone and first infraorbital bone in all examined specimens of Rhamphichthyoidea, and exhibits substantial interspecific variation in shape. We noted that this bone was absent in a 20.0 mm (small juvenile) individual of Brachyhypopomus diazi, collagenous in a 24.0 mm (small juvenile) specimen of M. bilineatus, and a 37.0 mm (small juvenile) of Rhamphichthys sp., partially ossified in 35.0–40.0 mm specimens of Brachyhypopomus sp. indet., a 40.0 mm of M. bilineatus, and 30.0–46.5 mm specimens of H. lepturus, and approximately 95% ossified in a 74.0 mm specimen of Brachyhypopomus sp. indet. (Fig. 2). This bone has previously been identified as the first infraorbital bone by Triques (1993: 98, fig. 5) and Mago-Leccia (1994: 175, fig. 77) and as the antorbital bone by Albert & Campos-da-Paz (1998) and Albert (2001). Further studies, involving ontogenetic series from multiple rhamphichthyoid species, will be needed to identify and provide a formal description of this bone. We suggest the following simple procedure (previously utilized by Weitzman, 1962: figs 8, 9 in the characiform Brycon meeki), for recognizing the antorbital bone, and numbering the infraorbital series in gymnotiforms. The antorbital bone, when present, is located below the posterior narial aperture and is parallel to the anterior inferior edge of the eye. The infraorbital series begins with the independent first infraorbital bone, or in some cases the fused first and second infraorbitals under the ventral border of the antorbital bone. The series follows with the second, third, and fourth infraorbital bones below the ventral margin of the eye. The fifth and sixth infraorbital bones are positioned parallel to the posterior margin of the eye. 10. Presence or absence of first infraorbital bone: (0) present; (1) absent (CI = 1.000; RI = 1.000). The first infraorbital bone is present in the secondary outgroups (state 0). It is absent in all species of Hypopygus, in Steg. cryptogenes, and in Steatogenys (state 1; Figs 3, 4). See comments above in introduction to ‘Supraorbital and infraorbital series, and associated structures’.


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12. Presence or absence of third infraorbital bone: (0) present; (1) absent (CI = 1.000; RI = 1.000).

infraorbital aperture is present in most Gymnotiformes, including the immediate outgroups to Hypopygus and Steg. cryptogenes (state 0). The infraorbital aperture is present in juveniles and adults of H. lepturus (the sister group to H. hoedemani and H. minissimus, see Fig. 1; Appendix 3). Conversely, adults of H. hoedemani and H. minissimus exhibit the derived loss of the aperture of the infraorbital canal (but not the canal itself) (state 1).

The third infraorbital bone is present in the secondary outgroups (state 0; Fig. 2). It is absent in all examined species of Hypopygus, in Steg. cryptogenes, and in Steatogenys (state 1; Figs 3, 4).

17. Presence or absence of parietal branch of supraorbital canal in adults: (0) presence of canal branch; (1) absence of canal branch (CI = 1.000; RI = 1.000).

13. Presence or absence of fourth infraorbital bone: (0) present; (1) absent (CI = 1.000; RI = 1.000).

The parietal branch of the supraorbital canal is present in all species of the immediate outgroups (state 0; Fig. 2; Mago-Leccia, Lundberg & Baskin, 1985: 5, fig 3). Conversely, ingroup members of Hypopygus and Steg. cryptogenes lack the parietal branch of the supraorbital canal over the frontal bone, constituting a synapomorphy for the two genera (state 1; Figs 3, 4; Appendix 3). The parietal branch of supraorbital canal is also completely absent in some early stages of the development in immediate outgroups, for example in a 41 mm specimen of Rhamphichthys sp., and in some species of the distantly related genus Gymnotus (e.g. Arratia & Huaquin, 1995: fig. 3D).

11. Presence or absence of second infraorbital bone: (0) present; (1) absent (CI = 1.000; RI = 1.000). The second infraorbital bone is present in the secondary outgroups (state 0; Fig. 2) but is absent in all ingroup species of Hypopygus, in Steg. cryptogenes, and also in Steatogenys (state 1; Figs 3, 4).

The fourth infraorbital bone is present in members of the immediate outgroups (state 0; Fig. 2). It is absent in all species of Hypopygus and in Steg. cryptogenes (state 1; Figs 3, 4). 14. Presence or absence of fifth infraorbital bone: (0) present; (1) absent (CI = 1.000; RI = 1.000). The fifth infraorbital bone is present in members of the immediate outgroups (state 0; Fig. 2). It is absent in all examined species of Hypopygus and in Steg. cryptogenes (state 1; Figs 3, 4). 15. Presence or absence of sixth infraorbital bone: (0) present; (1) absent (CI = 1.000; RI = 1.000). The presence of the sixth infraorbital bone was considered a synapomorphy for H. lepturus and H. neblinae by Mago-Leccia (1994). The sixth infraorbital bone is, however, absent in H. lepturus. In contrast, in Hypopygus isbruckeri, H. neblinae, Hypopygus nijsseni, Hypopygus ortegai, and in Steg. cryptogenes, the sixth infraorbital canal bone is present as an ossified canal tube positioned parallel to the posterior border of the eye (state 0; Fig. 3). The sixth infraorbital canal bone is present in members of the immediate outgroups, but its position in relation to the eye is variable. The loss of the sixth infraorbital bone in some Hypopygus species is an important aspect of reductive evolution within the genus. Hypopygus hoedemani, H. lepturus, and H. minissimus have lost the sixth infraorbital canal bone (state 1; Fig. 4; Appendix 3). 16. Presence or absence of infraorbital canal aperture: (0) present; (1) absent (CI = 1.000; RI = 1.000). The infraorbital canal aperture (following the nomenclature of Arratia & Huaquin, 1995) is located over the lateral portion of the frontal bone. It contacts ventrally with the dorsal portion of the sixth infraorbital canal bone (whenever it is present). The

18. Presence or absence of supraorbital canal: (0) present; (1) partially present; (2) absent (CI = 1.000; RI = 0.000). The supraorbital canal is present and extends anteriorly to the posterior portion of the nasal laterosensory canal in adults of H. isbruckeri, H. neblinae, H. nijsseni, H. ortegai, Steg. cryptogenes, and in members of the immediate outgroups (state 0; Figs 2, 3). It is present as an unossified canal in juveniles of H. lepturus, and in all available juvenile specimens of the remaining species of Hypopygus (see Appendix 3). The anterior portion of the supraorbital canal fails to ossify in H. minissimus (state 1; Fig. 4; Appendix 3). In H. hoedemani the entire supraorbital canal system, including its anterior portion fails to ossify (state 2). 19. Association of supraorbital canal and frontal bone in adults: (0) supraorbital canal is integral to frontal bone; (1) supraorbital canal independent from frontal bone (CI = 1.000; RI = 1.000). The partial independence of the supraorbital canal from the frontal bone was first proposed by MagoLeccia (1994) as a character used to diagnose Hypopygus. However, our analysis of a more encompassing group of species in Hypopygus revealed that the evolution of this character in the genus is more complex


HYPOPYGUS: PHYLOGENY AND TAXONOMIC REVISION than first thought. The supraorbital canal is integral to the frontal bone in all species of Hypopygus except H. lepturus, H. ortegai, and H. nijsseni, and in the immediate outgroups (state 0; Fig. 2). The supraorbital canal is independent from the frontal bone in H. lepturus, H. ortegai, H. nijsseni, and Steg. cryptogenes (state 1; Fig. 3). This character is not applicable to H. hoedemani and H. minissimus where the supraorbital canal is absent (see Character 18, above).

INTERMUSCULAR

BONES

20. Form of post-Weberian dorsal myorhabdoi: (0) post-Weberian dorsal myorhabdoi with simple ramification; (1) post-Weberian dorsal myorhabdoi with branched structure (CI = 1.000; RI = 1.000). As noted by Lundberg & Mago-Leccia (1986: 59, fig. 6), the post-Weberian dorsal myorhabdoi (therein named epineurals) have a highly branched structure in some gymnotiform genera. Our secondary outgroups possess post-Weberian dorsal myorhabdoi with a simple ramification (state 0). Post-Weberian dorsal myorhabdoi with a branched structure are present in Hypopygus, in Steg. cryptogenes, and in Steatogenys (state 1).

NEUROCRANIUM 21. Relative width of anterior dorsomedian fontanel: (0) wide; (1) narrow (CI = 1.000; RI = 1.000). Two dorsomedial cranial fontanels are usually present in species of Hypopygus, and in members of the immediate outgroups. Well-developed cranial fontanels were first proposed as a diagnostic character for Hypopygus by Mago-Leccia (1994: 50). However, this character only applies to a subset of species within the genus. The anterior fontanel typically is anteroposteriorly elongated with irregular lateral margins in most gymnotiforms (Hilton et al., 2007). The opening of the anterior fontanel is relatively wide (wider than the lateral portion of the frontal bone) in H. isbruckeri, H. neblinae, H. nijsseni, H. ortegai, and Steg. cryptogenes, and also in members of the immediate outgroups (state 0). The opening of the anterior fontanel is relatively narrow (narrower than the lateral portion of the frontal bone) in: H. hoedemani, H. lepturus, and H. minissimus (state 1; Appendix 3). 22. Presence or absence of vomer: (0) present; (1) absent (CI = 1.000; RI = 1.000). Mago-Leccia (1994), first proposed the absence of the vomer as a diagnostic character for Hypopygus. In all examined species of Hypopygus and Steg. cryptogenes

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the vomer is absent (state 1; de La Hoz & Chardon, 1975: 127, fig. 4e). In all immediate outgroups the vomer is present (state 0). The anterior portion of the vomer is located on the median or posterior portion of the ventral ethmoid, with the ventral ethmoid separate from the vomer, in Gymnorhamphichthys (de La Hoz & Chardon, 1975: 127, fig. 4b) and fused to the vomer in Rhamphichthys. In Steatogenys, adults possess the vomer fused to, and smaller than the ventral ethmoid. 23. Presence or absence of ventral ethmoid: (0) present; (1) absent (CI = 1.000; RI = 1.000). The ventral ethmoid is present in all members of the immediate outgroups (state 0). It is present and partially fused to the parasphenoid in H. neblinae (state 0). It is absent in H. hoedemani, H. isbruckeri, H. lepturus, H. minissimus, H. nijsseni, and H. ortegai and Steg. cryptogenes (state 1; de La Hoz & Chardon, 1975: 127, fig. 4e). 24. Presence or absence of lateral lamella on frontal bone: (0) absent; (1) present (CI = 1.000; RI = 0.000). A lateral lamella on the frontal bone is absent in Steatogenys (state 0) and in H. hoedemani. It is present to a variable extent, sometimes contacting the anterior portion of the sphenotic spine, in all ingroup members except H. hoedemani and in Gymnorhamphichthys and Rhamphichthys (state 1). 25. Presence or absence of extrascapular canal bones: (0) present; (1) reduced or completely absent (CI = 1.000; RI = 1.000). The extrascapular canal bones are present in most species of Gymnotiformes, including most of the ingroup members, and all immediate outgroups (state 0; Figs 2, 3; Hilton et al., 2007: 13, fig. 10A, B). In H. hoedemani and H. minissimus, the extrascapular canal bones are reduced or completely absent (state 1; Fig. 4; Appendix 3). 26. Presence or absence of first ossified postotic laterosensory canal bone: (0) present; (1) absent (CI = 1.000; RI = 1.000). The first ossified postotic laterosensory canal bone is present and located over the supracleithrum, anterior to the extrascapular, in all ingroup species except H. hoedemani and H. minissimus, Steatogenys, Rhamphichthys, Brachyhypopomus, Microsternarchus, and Racenisia (state 0; Figs 2, 3). The first ossified laterosensory canal bone is present and fused to the supracleithrum in Gymnorhamphichthys. The first ossified laterosensory canal bone is absent in H. hoedemani and H. minissimus (state 1; Fig. 4; Appendix 3).


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27. Form of posterior portion of the ossified Baudelot’s ligament: (0) narrow; (1) wide (CI = 1.000; RI = 1.000). An ossification that extends from the medial surface of the pectoral girdle anteriorly to an insertion on the portion of the basioccipital situated posteroventral to the lagenar capsule is recognized here as a homologous structure to Baudelot’s ligament, present in most gymnotiforms. In Hypopygus, Steg. cryptogenes, Steatogenys, Gymnorhamphichthys, Rhamphichthys, Hypopomus, Brachyhypopomus, Microsternarchus, and Racenisia, Baudelot’s ligament is ossified. The posterior portion of the ossified Baudelot’s ligament is narrow in the secondary outgroups (state 0). It is distinctly wider distally in all ingroup members, and in the proximate outgroup (state 1).

PALATINE

hyomandibula endopterygoid

metapterygoid

symplectic

ARCH

28. Anterodorsally directed process on dorsal margin of metapterygoid: (0) absent; (1) present (CI = 1.000; RI = 0.000). The dorsal margin of the metapterygoid is straight or irregular, without an anterodorsally directed process in all species of Hypopygus except H. neblinae, Steg. cryptogenes, and all the immediate outgroup taxa (state 0; Fig. 8). A prominent anterodorsally directed process on the dorsal margin of the metapterygoid is present in H. neblinae (state 1; Fig. 9).

PECTORAL

GIRDLE

29. Association of supracleithrum and post-temporal: (0) supracleithrum fused to post-temporal; (1) supracleithrum independent from post-temporal (CI = 1.000; RI = 1.000). Triques (1993) mistakenly reported that the posttemporal is fused to the supracleithrum in Hypopygus. In contrast, Mago-Leccia (1994) proposed the post-temporal separate from the supracleithrum as a diagnostic character for Hypopygus. We observed that the supracleithrum is fused to the post-temporal in Steatogenys, Gymnorhamphichthys, and Rhamphichthys (state 0; Mago-Leccia, 1978: 60, fig. 14; MagoLeccia et al., 1985: 8, fig. 6). In Hypopygus and Steg. cryptogenes, the supracleithrum is separated from the small to sometimes tiny post-temporal [state 1; Mago-Leccia, 1978: 66, fig. 28 for Sternopygus macrurus (Bloch & Schneider)]. 30. Presence or absence of mesocoracoid bridge: (0) presence; (1) absence (CI = 0.500; RI = 0.000). The mesocoracoid bridge is present in Steatogenys and Rhamphichthys (state 0; Albert, 2001: 48–49,

preopercle

quadrate

Figure 8. Posterior portion of endopterygoid and quadrate, metapterygoid, symplectic, and adjoining bones in Steatogenys duidae MCP 31952 (WC14.240899), immature, 122 mm; left side, lateral view, anterior to left; larger stippling represents cartilage.

figs 33, 34), and absent in Hypopygus, Steg. cryptogenes, and Gymnorhamphichthys (state 1). 31. Presence or absence of an extension of posteroventral portion of coracoid: (0) present; (1) absent (CI = 0.500; RI = 0.750). An extension of the posteroventral portion of the coracoid is present in H. neblinae, in Steg. cryptogenes, and in all immediate outgroups species (state 0; Fig. 10). It is absent in the remaining species of Hypopygus (state 1; Fig. 11).

HYOID

ARCH

32. Presence or absence of anterior-most branchiostegal ray: (0) present; (1) absent (CI = 0.500; RI = 0.750). The homology of the branchiostegal rays was discussed by de Santana & Vari (2010: 246–247). The anterior-most branchiostegal ray attaching to the ventral margin of the anterior ceratohyal is present in H. hoedemani and H. minissimus, and in Steatogenys, Gymnorhamphichthys, and Rhamphichthys (state 0; Fig. 12). It is absent in all remaining species of


HYPOPYGUS: PHYLOGENY AND TAXONOMIC REVISION anterodorsally-directed process hyomandibula endopterygoid

metapterygoid

symplectic

quadrate

preopercle

Figure 9. Posterior portion of endopterygoid and quadrate, metapterygoid (with anterodorsally directed process), symplectic, and adjoining bones in Hypopygus neblinae UF 1480540 (WC12.130304), female, 75 mm; left side, lateral view, anterior to left; larger stippling represents cartilage.

Hypopygus, and in Steg. cryptogenes (state 1; Fig. 13). The presence of four branchiostegal rays was suggested as a synapomorphy for Hypopygus by MagoLeccia (1994), Albert & Campos-da-Paz (1998), and Albert (2001). Nonetheless, our examination of a more encompassing group of species of Hypopygus demonstrates that this character is not a synapomorphy at the genus level.

GILL

ARCHES

33. Presence or absence of medial ridge on posterior portion of dorsal surface of basihyal: (0) present; (1) absent (CI = 1.000; RI = 1.000). A medial ridge is present on the posterior portion of the dorsal surface of basihyal in all species of Hypopygus except for H. hoedemani, H. lepturus, and H. minissimus, in Steg. cryptogenes, and in Gymnorhamphichthys and Rhamphichthys (state 0; de Santana & Vari, 2010: figs 15–17). The posterior portion of the dorsal surface of basihyal is smooth (ridge absent) in H. hoedemani, H. lepturus, and H. minissimus, and in Steatogenys (state 1; Fig. 14). 34. Ossification of second basibranchial: (0) ossified; (1) unossified (CI = 0.500; RI = 0.500). Members of the ingroup, and all examined outgroups possess five basibranchials. We identified an element located ventrally to the basihyal between the first

1111

hypobranchials as the first basibranchial (de La Hoz & Chardon, 1984: 30–31, figs 18, 19). Variation in the number of elements involves differences in the number of ossified basibranchials. Several authors have used the total number of ossified basibranchials in reconstructions of phylogenetic relationships (e.g. Albert, 2001), or as a diagnostic character for genera – for instance the presence of two ossified basibranchials proposed as diagnostic by Mago-Leccia (1994) for Hypopygus. We also found that the ossification (or non-ossification) of individual basibranchial elements provides phylogenetic resolution, as outlined below. The first basibranchial is ossified in B. brevirostris, and cartilaginous in Hypopygus, Steg. cryptogenes, and immediate outgroups. Within Hypopygus, the second to fifth basibranchials are phylogenetically informative, and are discussed below. The second basibranchial is ossified in H. isbruckeri, H. lepturus, H. neblinae, H. nijsseni, and H. ortegai and in all examined species of the immediate outgroups (state 0; de Santana & Vari, 2010: figs 15– 17). The second basibranchial is unossified in H. hoedemani, H. minissimus, and in Steg. cryptogenes (state 1; Fig. 14). 35. Ossification of third basibranchial: (0) unossified; (1) ossified (CI = 1.000; RI = 0.000). The third basibranchial is unossified in all species of the immediate outgroups, and also in H. hoedemani, H. isbruckeri, H. lepturus, H. minissimus, H. neblinae, and Steg. cryptogenes (state 0; Fig. 14). The third basibranchial is ossified in H. ortegai (state 1; de Santana & Vari, 2010: figs 15–17). 36. Ossification of fourth basibranchial: (0) unossified; (1) ossified (CI = 1.000; RI = 0.000). The fourth basibranchial is unossified in all species of the immediate outgroups, all species of Hypopygus except H. nijsseni, and Steg. cryptogenes (state 0; Fig. 14). It is ossified in H. nijsseni, and independent in B. brevirostris (state 1). 37. Ossification of fifth basibranchial: (0) unossified; (1) ossified (CI = 1.000; RI = 0.000). The fifth basibranchial is unossified in all species of the immediate outgroups, all species of Hypopygus except H. nijsseni, and Steg. cryptogenes (state 0; Fig. 14). It is ossified in H. nijsseni (state 1).

SYMPLECTIC,

HYOMANDIBULA, OPERCULAR SERIES,

AND RELATED SENSORY CANALS

38. Presence or absence of the ventral preopercular sensory canal: (0) present; (1) absent (CI = 1.000; RI = 1.000).


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C. D. DE SANTANA and W. G. R. CRAMPTON cleithrum

scapula

pectoral radials 1-2

pectoral radials 3-4

coracoid extension of posteroventral portion of coracoid Figure 10. Pectoral girdle of Hypopygus cryptogenes MZUSP 30088, 147 mm; left side, medial view, anterior to left, inverted figure. Note the extension of the posteroventral portion of the coracoid.

scapula pectoral radials 1-2

pectoral radials 3-4 cleithrum

coracoid

Figure 11. Pectoral girdle of Hypopygus ortegai, UF 148540 (WC04.160104), 130 mm; left side, medial view, anterior to left, inverted figure.

Two or more sensory canals are present on the preopercle in the secondary outgroups as ossified elements or soft tissues (Fig. 2). The ventral and dorsal sensory canals are present in most species of Hypopygus, Steg. cryptogenes, and in Steatogenys (state 0, Fig. 3). Within Hypopygus, the ventral preopercular sensory

canal is absent in H. hoedemani, H. lepturus, and H. minissimus (state 1; Fig. 4). 39. Presence or absence of the dorsal preopercular sensory canal: (0) present; (1) absent (CI = 1.000; RI = 1.000).


HYPOPYGUS: PHYLOGENY AND TAXONOMIC REVISION dorsal hypohyal

anterior ceratohyal

1113

interhyal

posterior ceratohyal ventral hypohyal

branchiostegals 1-2 branchiostegals 3-5

Figure 12. Hyoid arch of Hypopygus minissimus UF 148533 (WC41.120304), female, 43 mm; left side, lateral view, anterior to left; larger stippling represents cartilage. Striations represent ligament. Note presence of first branchiostegal ray.

The dorsal preopercular sensory canal is present in most species of Hypopygus, Steg. cryptogenes, and the immediate outgroups (state 0; Fig. 2). It is completely absent in H. hoedemani, H. lepturus, and H. minissimus (state 1; Fig. 4). 40. Association of preopercular sensory canals and preopercle: (0) preopercular sensory canals integral to preopercle; (1) last sensory canal fused to preopercle (CI = 1.000; RI = 1.000). The dorsal-most preopercular sensory canal is integral to the preopercle in Gymnorhamphichthys and Rhamphichthys (state 0). The ventral sensory canals are independent from the preopercle, and the last sensory canal is fused to the preopercle in most species of Hypopygus, Steg. cryptogenes, and Steatogenys (state 1). This character is not applicable to H. hoedemani, H. lepturus, and H. minissimus (see Character 39).

FINS

(Triques, 1996), Rhamphichthys 302 to 411 (Triques, 1999), and Steatogenys 110 to 196 (Crampton et al., 2004). The number of anal-fin rays in Stea. duidae increase proportionally with the length to the end of anal fin. For example, a specimen of 56 mm LEA (MCP 31957, WC02.300600) has 120 anal-fin rays, whereas a specimen of 93 mm LEA (MCNG 21672) possesses 165 anal-fin rays. Within the ingroup, adults of H. hoedemani, H. lepturus, and H. minissimus possess a maximum of 135 anal-fin rays. Hypopygus hoedemani and H. minissimus have the lowest maximum number of anal-fin rays amongst all Gymnotiformes (102 to 118, respectively). The remaining species of Hypopygus possess more than 136 anal-fin rays (state 0). Stegostenopos cryptogenes has the highest counts (148 to 172 rays). The presence of a low number of anal-fin rays in H. hoedemani, H. lepturus, and H. minissimus (state 1) is interpreted as a reductive character within the context of the phylogenetic reconstruction presented herein.

41. Number of anal-fin rays in adults: (0) more than 136; (1) fewer than 135 (CI = 1.000; RI = 1.000).

SCALES

Amongst the members of the immediate outgroup, Gymnorhamphichthys possesses 146 to 167 anal-fin rays (Mago-Leccia, 1994), Iracema 240 to 266

42. Presence or absence of scales on mid-dorsal region of body: (0) scales present; (1) scales absent (CI = 0.500; RI = 0.000).


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C. D. DE SANTANA and W. G. R. CRAMPTON dorsal hypohyal

anterior ceratohyal

interhyal

posterior ceratohyal ventral hypohyal

branchiostegals 1-2 branchiostegals 3-4 Figure 13. Hyoid arch of Hypopygus neblinae UF 148540 (WC12.130304), female, 81 mm; left side, lateral view, anterior to left; larger stippling represents cartilage. Striations represent ligament. Note absence of first branchiostegal ray.

cb1 cb5

bh bb2

bb4

bb3

bb5

ib2 ib4 hb1 up

eb5

ep1

Figure 14. Ventral portion of the gill arches of Hypopygus hoedemani, MZUSP 81488, 47.7 mm TL; dorsal view, anterior to left. Abbreviations: bb, basibranchial; bh, basihyal; cb, ceratobranchial; eb, epibranchial; hb, hypobranchial; ib, infrapharyngobranchial; up, upper pharyngeal tooth-plate. Note the posterior portion of the dorsal surface of the basihyal does not bear a ridge and the lack of ossification of the second to fifth basibranchial. Note also the well-developed pharyngeal teeth on cb5. Right dorsal portion of the gill arches not illustrated.


HYPOPYGUS: PHYLOGENY AND TAXONOMIC REVISION Scales are present along the mid-dorsal region in all species of Hypopygus except H. minissimus, and in Steg. cryptogenes (state 0). The scales of the midbody are lost in H. minissimus (state 1). Scales are also absent on the midbody in Gymnorhamphichthys (which is scale-free everywhere except on the caudal peduncle). 43. Presence or absence of scales over anal-fin pterygiophores: (0) present; (1) completely absent; (2) present only in anterior portion of body, anterior to approximately the 20th anal fin ray (CI = 1.000; RI = 1.000). In Steatogenys and in Rhamphichthys, the anal-fin pterygiophores are densely covered with scales (state 0). In contrast, the anal-fin pterygiophores are scalefree in Gymnorhamphichthys (see comments under Character 42; state 1). The anal-fin pterygiophores are partially scaled in Hypopygus and Steg. cryptogenes (state 2) where they are covered with scales only over the anterior portion, until approximately the 20th ray, and unscaled posteriorly.

PIGMENTATION 44. Presence or absence of oblique bands on lateral portion of body: (0) present; (1) absent (RI = 1.000; CI = 0.000). Oblique bands on the lateral portion of body are present in most species of Hypopygus, in Steg. cryptogenes, and in most members of the immediate outgroups (state 0). Oblique bands are completely absent in H. minissimus (state 1).

MISCELLANEOUS 45. Presence or absence of opaque tissue covering base of anal fin: (0) absent; (1) present (CI = 1.000; RI = 1.000). The presence of an opaque tissue covering the base of the anal fin was reported by Mago-Leccia (1978) as a synapomorphy for Hypopomus, Hypopygus, Microsternarchus, and Steatogenys. However, we did not find this character in Steatogenys. Therefore, it is absent in the immediate outgroups (state 0). In Hypopygus and Steg. cryptogenes, opaque tissue covers approximately 5 to 10% of the base of the anal-fin (state 1). A similar (apparently nonhomologous) tissue is present in members of the distantly related genera Brachyhypopomus, Hypopomus, Microsternarchus, and Racenisia. 46. Form of lateral line: (0) continuous; (1) intermittent (CI = 1.000; RI = 1.000).

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An incomplete lateral line was first suggested by Mago-Leccia (1994) as diagnostic of the genus Hypopygus. Members of the immediate outgroups possess a continuous lateral line (state 0). Hypopygus and Steg. cryptogenes possess a discontinuous lateral line (state 1). 47. Position of humeral electric organ: (0) axillary, dorsal to pectoral fin; (1) immediately posterior to base of pectoral fin (CI = 1.000; RI = 1.000). Hypopygus and Steg. cryptogenes possess a paired accessory electric organ (EO) located immediately posterior to the base of the pectoral fin (state 1, Fig. 15). This EO is mostly hidden from view in preserved specimens where the pectoral fin is flattened against the flank in its normal posterior position. The accessory EO is located in a wide groove, which continues as two narrower grooves – a long dorsal groove and a shorter ventral groove. The dorsal groove runs dorsally and then inflects sharply towards the head, and continues as a narrowing groove that reaches in some species within one to three orbital diameters of the eye. Triques (1997: 2, fig. 1) regarded this groove and the associated accessory EO as a synapomorphy uniting Hypopygus and Steg. cryptogenes. The ventral groove (which Triques did not comment on) runs in an anterior direction ventral to the base of the pectoral fin base, stopping just anterior to the pectoral fins’ base. The entire groove is filled with a translucent jelly-like substance, which overlies the EO and presumably serves to conduct electric current towards the rostral portion of the head. Species of Steatogenys possess a humeral accessory EO with a dorsal groove extending posteriorly, parallel to the lateral line, and located above the origin of the pectoral fin at the humeral region (state 0, Nijssen & Isbrücker, 1972: 161, fig. 1; Schwassmann, 1984: 111, fig. 6; Triques, 1997: 3, fig. 3; Crampton et al., 2004: 83, fig. 3). This structure was hypothesized to be homologous to the postpectoral accessory EO present in Hypopygus by Albert & Campos-daPaz (1998) and Albert (2001). Accessory EOs are unknown in Gymnorhamphichthys, Iracema, and Rhamphichthys. The accessory EOs of Hypopygus and Stegostenopos differ considerably in position, orientation, and electrocyte configuration to those of Steatogenys. For instance, the postpectoral EO of Hypopygus and Steg. cryptogenes is made up of a single-layered block of electrocytes, comprising two columns and four to seven rows of electrocytes, whereas the humeral EO of Steatogenys comprises c. 20 electrocytes organized in a single series (Crampton et al., 2004; Crampton, pers. observ.). There is also no ventral groove in the


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C. D. DE SANTANA and W. G. R. CRAMPTON dorsal groove

electrocytes

ventral groove Figure 15. Postpectoral accessory electric organ and associated dorsal and ventral grooves of Hypopygus nijsseni MCP 44737, 75 mm; left side, lateral view, anterior to left.

humeral EO in Steatogenys. The mental accessory EO is absent in Hypopygus and Steg. cryptogenes. Nonetheless, we follow Albert & Campos-da-Paz (1998) and Albert (2001) in regarding the humeral EO of Steatogenys and the postpectoral EO of Hypopygus as homologous structures. This hypothesis infers that a single accessory organ originated in the common ancestor of Hypopygus and Steatogenys and that the morphology of this organ subsequently diverged in the daughter lineages. The alternative hypothesis of an independent origin of accessory EOs in these two lineages is less parsimonious (assuming that Hypopygus and Steatogenys are sister taxa). However, detailed neuroanatomical studies of the innervations of accessory EOs in the Steatogenini, and ontogenetic studies of accessory EO development may be necessary to reject or confirm this alternative hypothesis.

UNUTILIZED

CHARACTERS

Based on a more encompassing group of Hypopygus species, and a more extensive series of specimens, our analyses raised questions about the utility of some of the characters used in previous studies to diagnose the monophyly of Hypopygus. For instance, most of the characters listed under Mago-Leccia’s (1994: 50) diagnosis of Hypopygus are plesiomorphies at the

generic level, and therefore non-informative. Such characters and the perceived problems with their utilization are discussed below. These unutilized characters are numbered sequentially with a leading ‘U’ to distinguish them from phylogenetically informative characters. They are organized by discrete body systems in an approximately anterior to posterior order. U1. Small body size. A small body size was proposed as a synapomorphy for Hypopygus by Triques (1997: 3), Albert & Campos-da-Paz (1998: 426), and Albert (2001: 69). The body size reduction in itself does not represent an independent hypothesis of homology in the genus given that it is associated with many reductions and simplifications in the skeleton of species of Hypopygus, which we have considered as individual characters. U2. Roundish snout. Triques (1997: 3) suggested the presence of a roundish snout as a synapomorphy for Hypopygus and Steg. cryptogenes. However this character does not apply to all the species in the genus, e.g. H. hoedemani. Moreover, some species of the proximate outgroup possesses a distinctly roundish snout, e.g. Stea. duidae and Steatogenys ocellatus (Crampton et al., 2004: figs 2, 4). U3. Urogenital papilla well developed. Mago-Leccia (1994: 50) suggested the presence of a well-developed urogenital papilla as a synapomorphy for Hypopygus.


HYPOPYGUS: PHYLOGENY AND TAXONOMIC REVISION The urogenital papilla in most Gymnotiformes is well developed in the breeding season, and less pronounced during nonreproductive periods. We did not observe any unusual development of the urogenital papilla in Hypopygus or Steg. cryptogenes relative to outgroups. U4. Nares remote. Mago-Leccia (1994: 50) suggested the presence of posterior nares, located distantly from the anterior nares, near the eye, as a synapomorphy for Hypopygus. However, Triques (1997), Albert & Campos-da-Paz (1998), and Albert (2001) documented the unequivocal absence of the posterior nares in Hypopygus and Steg. cryptogenes. We likewise documented the absence of the posterior nares in all Hypopygus, and in Steg. cryptogenes. U5. Premaxilla small, laminar, and conical. Premaxilla small, laminar, and conical was proposed as a synapomorphy for Hypopygus by Albert & Camposda-Paz (1998: 426) and Albert (2001: 69). However, we documented the premaxilla in Steatogenys to be comparable in shape to the premaxilla in Hypopygus. U6. Absence of teeth on jaws. Mago-Leccia (1994: 50) proposed the absence of teeth in both jaws as a synapomorphy for Hypopygus. However, the jaws in all examined adult specimens of the immediate outgroups are also toothless. U7. Mesethmoid short. Mago-Leccia (1994: 50) suggested a short mesethmoid as a synapomorphy for Hypopygus. The mesethmoid in Hypopygus is, however, as short as it is in Steatogenys. Therefore, this character is not indicative of the monophyly of Hypopygus. U8. Endopterygoid elongate with a tiny ascending process. An elongated endopterygoid was suggested by Mago-Leccia (1994: 50; mesopterygoid therein) as a synapomorphy for Hypopygus. However, the endopterygoid in all species of Hypopygus is in fact relatively short, resembling the condition in Steatogenys. The endopterygoid in the Steatogenini is shorter than in Gymnorhamphichthys and Rhamphichthys. Mago-Leccia (1994) also suggested the presence of a tiny ascending process on the endopterygoid as a synapomorphy for Hypopygus. However, we documented the presence of this process not only in Hypopygus and Steg. cryptogenes but also in the proximate outgroup Steatogenys, and in all the secondary outgroups. U9. Absence of lateral ethmoid. The absence of the lateral ethmoid was listed by Mago-Leccia (1994: 50) as a synapomorphy for Hypopygus. The lateral ethmoid is, however, also absent in all members of the immediate outgroups. U10. Four pectoral radials. Mago-Leccia (1994: 50) suggested the presence of four pectoral radials as a synapomorphy for Hypopygus. Four pectoral

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radials are, however, present in species of Gymnorhamphichthys and Rhamphichthys. Three pectoral radials are present in members of Steatogenys (this being a putative synapomorphy for the genus Steatogenys). Albert & Campos-da-Paz (1998: 426) and Albert (2001: 69) suggested the separation of the third and fourth pectoral radials as a synapomorphy for Hypopygus. However, we noted that the fourth and fifth pectoral radials are also separate in Gymnorhamphichthys and Rhamphichthys. An ontogenetic series of Steatogenys is not, as yet, available in order to distinguish whether the third and fourth pectoral radials are fused or whether, alternatively, the fourth pectoral radial is simply lost during ontogeny. In either case this character would be a synapomorphy to species of Steatogenys rather than an unambiguous synapomorphy for Hypopygus. U12. Urohyal enlarged. An enlarged urohyal was listed by Mago-Leccia (1994: 50) as a synapomorphy for Hypopygus. However, the enlarged urohyal condition is also present in Steatogenys. U13. Gill rakers with three to four fleshy lobes. MagoLeccia (1994: 50) proposed the presence of three to four fleshy lobes on the gill rakers as a synapomorphy for Hypopygus. However, similar gill rakers are also present in all the immediate outgroups. U14. Basihyal short. Mago-Leccia (1994: 50) suggested a short, shovel-like basihyal as a synapomorphy for Hypopygus. A similar basihyal is, however, present in Steatogenys. U15. Posterior process of fifth epibranchial short. Albert & Campos-da-Paz (1998: 426) and Albert (2001: 69) proposed the posterior process of the fifth epibranchial short as a synapomorphy for Hypopygus. However, this process is also short in Steatogenys. U16. Seventh epibranchial with posterior process. Albert & Campos-da-Paz (1998: 426) proposed the seventh epibranchial with posterior process as a synapomorphy for Hypopygus. However, this cannot be the case, as there are only five epibranchials in gymnotiforms (e.g. Mago-Leccia, 1978: fig. 17; Hilton et al., 2007: fig. 14; de Santana & Vari, 2010: fig. 18). U17. Three ossified infrapharyngobranchials. MagoLeccia (1994) proposed three ossified infrapharyngobranchials as a synapomorphy for Hypopygus. However, this is the typical condition in Gymnotiformes (Mago-Leccia, 1978: 56, fig. 7; de Santana & Vari, 2010: fig. 18). U18. First unossified infrapharyngobranchial. Albert (2001: 69) proposed the first infrapharyngobranchial unossified as a synapomorphy for Hypopygus. However, we noted that this character is also found in all immediate outgroups.


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U19. Precaudal vertebrae 13–14. The possession of 13 to 14 precaudal vertebrae was proposed as a synapomorphy for Hypopygus by Mago-Leccia (1994: 50). However, our examination of a more encompassing group of Hypopygus species demonstrated that the number of precaudal vertebrae varies from 14 to 16, which overlaps considerably with the immediate outgroups and other gymnotiform taxa (see Taxonomic accounts). U20. Body cavity short, 11 or fewer precaudal vertebrae. Both Mago-Leccia (1994: 50) and Albert & Campos-da-Paz (1998) used the number of precaudal vertebrae as a synapomorphy for Hypopygus. Albert & Campos-da-Paz (1998: 426) proposed the presence of 11 or fewer precaudal vertebrae, whereas MagoLeccia (1994) proposed the presence of 13 to 14 precaudal vertebrae. We found 14 to 16 precaudal vertebrae in Hypopygus.

Table 2. Nominal species assigned to Hypopygus. Species are arranged alphabetically with original generic epithet and authorship Nominal species

Assignment herein

Stegostenopos cryptogenes Triques Hypopygus hoedemani sp. nov. Hypopygus isbruckeri sp. nov. Hypopygus lepturus Hoedeman Hypopygus minissimus sp. nov. Hypopygus neblinae Mago-Leccia Hypopygus nijsseni sp. nov. Hypopygus ortegai sp. nov.

Hypopygus cryptogenes Hypopygus hoedemani Hypopygus isbruckeri Hypopygus lepturus Hypopygus minissimus Hypopygus neblinae Hypopygus nijsseni Hypopygus ortegai

DISCUSSION THE

TAXONOMY AND STATUS OF THE GENUS

STEGOSTENOPOS

Triques (1997) established Stegostenopos based on the presence of a dorsal groove on the head extending from the postpectoral accessory EO to the eye, and the presence of scattered chromatophores on the anal fin rays and membranes. Stegostenopos was later listed, without clarification, as a junior synonym of Steatogenys Boulenger (Albert & Campos-da-Paz, 1998; Albert, 2001). Without further explanation, Stegostenopos was then resurrected in Albert & Crampton’s (2003) contribution to Reis, Kullander & Ferraris’s (2003) catalogue of Neotropical freshwater fishes. As noted earlier, a prominent dorsal groove on the head extending anteriorly from the postpectoral accessory EO is also present in all species of Hypopygus (see Fig. 15). Additionally, the presence of scattered chromatophores on the anal-fin rays and membranes is shared with H. neblinae and some individuals of H. lepturus. Moreover, all 13 synapomorphies proposed for Hypopygus are present in Stegostenopos. Based on the evidence summarized above, and using our final tree topology (Fig. 1) as a working classification, we therefore assign Stegostenopos as a junior synonym of Hypopygus. Henceforth in this paper we refer to Steg. cryptogenes as Hypopygus cryptogenes (Table 2).

SYNAPOMORPHY

SCHEME IN THE GENUS

HYPOPYGUS

The six lettered clades (A-F) in Figure 1, and in the following list, are present in the most parsimonious tree recovered during cladistic analysis. A list of the character state transitions that optimize unambigu-

ously, or as ACCTRAN, at the branch encompassing each numbered clade is provided below, as are transitions that optimized as autapomorphies for species. We limited the discussion to characters pertinent to the hypothesis of relationship within Hypopygus, and collapse all outgroups into one branch in Figure 1. A brief description of each synapomorphy is provided below. More detailed information is available under the description of all 47 characters, above. Each synapomorphic character state transition for Hypopygus (or a subunit of that genus) is followed by information on whether that state transition is a reversal within Hypopygus, whether other clades within Hypopygus have acquired that character state independently, and whether additional character state transitions in the character under discussion occur within the clade defined by the synapomorphy. Bremer support (BR) for each clade is provided.

Clade A: Hypopygus Diagnosis (BR = 12): Character 1, state 0→1; anterior nares located inside upper lip Character 2, state 0→1; loss of posterior nares Character 13, state 0→1; loss of fourth infraorbital bone Character 14, state 0→1; loss of fifth infraorbital bone Character 17, state 0→1; loss of parietal branch of supraorbital canal Character 22, state 0→1; loss of vomer Character 29, state 0→1; supracleithrum independent from post-temporal


HYPOPYGUS: PHYLOGENY AND TAXONOMIC REVISION Character 30, state 0/1→1 (ACCTRAN); absence of mesocoracoid bridge Character 32, state 0→1 loss of anterior most branchiostegal ray, reversed in clade F Character 43, state 0→2 anterior portion of anal-fin pterygiophores covered by scales Character 45, state 0→1; presence of opaque tissue covering base of anal fin Character 46, state 0→1; lateral line intermittent Character 47, state 0→1; presence of postpectoral accessory electric organ Hypopygus neblinae Character 28, state 0→1; presence of anterodorsallydirectly process on dorsal margin of metapterygoid Clade B: Hypopygus cryptogenes, H. hoedemani, H. isbruckeri, H. lepturus, H. minissimus, H. nijsseni, H. ortegai Diagnosis (BR = 2): Character 23, state 0→1; absence of ventral ethmoid Character 31, state 0→1; absence of an extension of posteroventral portion of coracoid; reversed in H. cryptogenes Clade C: Hypopygus cryptogenes, H. hoedemani, H. lepturus, H. minissimus, H. nijsseni, H. ortegai Diagnosis (BR = 1) Character 19, state 0→1; supraorbital canal independent from frontal bone Hypopygus nijsseni Character 36, state 0→1; fourth basibranchial ossified Character 37, state 0→1; fifth basibranchial ossified Hypopygus ortegai Character 35, state 0→1; third basibranchial ossified Clade D: Hypopygus cryptogenes, H. hoedemani, H. lepturus, H. minissimus Diagnosis (BR = 1) Character 5, state 0→1; posterodorsal margin of the dentary concave Character 34, state 0→0/1 (ACCTRAN); second basibranchial unossified; reversed in H. lepturus Hypopygus cryptogenes Character 31, state 1→0; presence of an extension of posteroventral portion of coracoid Character 34, state 0/1→1 (ACCTRAN); second basibranchial unossified Clade E: Hypopygus hoedemani, H. lepturus, H. minissimus Diagnosis (BR = 7) Character 8, state 0→1; loss of fourth mandibular canal bone Character 9, state 0→1; loss of fifth mandibular canal bone

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Character 15, state 0→1; loss of sixth infraorbital bone Character 21, state 0→1; anterior dorsomedian fontanel narrow Character 33, state 0→1; absence of medial ridge on posterior portion of dorsal surface of basihyal Character 38, state 0→1; loss of ventral preopercular sensory canal Character 39, state 0→1; loss of dorsal preopercular sensory canal Character 41, state 0→1; reduced number of anal-fin rays in adults, fewer than 135 Hypopygus lepturus Character 34, state 0/1→0 (ACCTRAN); second basibranchial ossified Clade F: Hypopygus hoedemani, H. minissimus Diagnosis (BR = 7) Character 3, state 0→1; loss of nasal laterosensory canal Character 4, state 0→1; descending process of maxilla broad; also present in M. bilineatus Character 7, state 0→1; loss of third mandibular canal bone Character 16, state 0→1; loss of infraorbital canal aperture Character 18, state 0→0/1/2 (ACCTRAN); partial or total loss of supraorbital canal Character 25, state 0→1; partial or total loss of extrascapular canal Character 26, state 0→1; loss of first ossified postotic canal of lateral line Character 32, state 1→0; presence of anterior most branchiostegal ray attaching to ventral margin of anterior ceratohyal; also present in Stea. duidae Character 34, state 0/1→1 (ACCTRAN); second basibranchial unossified; also present in some other species of Hypopygus Hypopygus hoedemani Character 18, state 0/1/2→ 2 (ACCTRAN); loss of supraorbital canal Hypopygus minissimus Character 6, state 0→1; loss of second mandibular canal bone Character 18, state 0/1/2→ 1 (ACCTRAN); loss of anterior portion of supraorbital canal Character 42, state 0→1; loss of scales along the mid-dorsal region of body Character 44, state 0→1; loss of oblique bands on lateral and dorsal regions of body

PHYLOGENY

AND MINIATURIZATION IN

HYPOPYGUS

The evolution of miniaturization in Hypopygus Miniaturization and associated reductive character evolution by paedomorphic processes (i.e. where


1120


Table 3. Minimum size of maturity in Hypopygus, measured: as total length (TL), length to the end of the anal fin (LEA), and snout to the posterior end of the body cavity (BC) Species Hypopygus Hypopygus Hypopygus Hypopygus Hypopygus Hypopygus Hypopygus Hypopygus

cryptogenes hoedemani isbruckeri lepturus minissimus neblinae nijsseni ortegai

TL (mm)

LEA (mm)

BC (mm)

89 42.7 75 84 42 73 72 98

52 32 53 53 31 46 53 66

19.6 17.8 16.2 19.2 15.8 16.2 18.7 21.3

juvenile characters are retained in sexually mature adults) is part of the wider phenomenon of heterochrony (i.e. evolutionary changes in the timing and rate of developmental events, and their consequences), which has been documented in several groups of Neotropical fishes (e.g. Schaefer et al., 1989; Buckup, 1993; Lovejoy, Iranpour & Collette, 2004). However, determining which general form of heterochrony is responsible for reductive evolutionary changes in morphology is intractable in most groups of Neotropical fishes, including Hypopygus, where morphological ontogeny has not been adequately characterized (see Fink, 1982). Where ontogenetic data are lacking, miniaturization can only be studied as a historical event in the context of phylogenetic reconstructions (Fink, 1982, 1988; Buckup, 1993). Based on character transitions indicative of reductive morphological evolution in our final tree topology (Fig. 1), we hypothesize that miniaturization occurred three times in Hypopygus: once at the base of clade A, again at the base of clade E, and once more at the base of clade F. With the exception of H. cryptogenes and H. ortegai, most species of Hypopygus mature below 20 mm BC, and this reduction also appears to occur increasingly from clade A to F (see Fig. 1 for reductive characters, and Table 3 for body sizes). Reductive characters associated with miniaturization comprise approximately 44.6% of the total number of characters in the Hypopygus phylogeny. Moreover, the immediate outgroups to Hypopygus do not contain miniaturized species. For instance, Steatogenys have relatively large adult body sizes, ranging from a maximum of 209 mm in Stea. duidae to 405 mm in Stea. ocellatus (Crampton et al., 2004). Likewise, Gymnorhamphichthys and Rhamphichthys all mature at more than 100 mm – and mostly more than 300 mm. Thus, on grounds of size, as well as on grounds of morphological character evolution, we propose that Hypopygus qualifies as a case of miniaturization. If we are

correct in our interpretation, the scenario in the Steatogenini resembles the progressive phylogenetic reduction in body sizes described by de Pinna (1996) for catfishes, in which miniaturization is a terminal state in a progressive decrease in size amongst closely related taxa (relative to the body size present in outgroups). This scenario of a progressive phylogenetic reduction in Hypopygus represents an exception to Cope’s rule, i.e. that size usually increases within lineages (Stanley, 1973; McKinney, 1990; Hanken & Wake, 1993).

Patterns of reductive character evolution and their contribution to phylogenetic reconstruction in Hypopygus Some authors have argued that the homology of reductive characters is not testable by correspondence, because missing characters simply cannot be compared (e.g. Hecht & Edwards, 1977). However, Weitzman & Fink (1985) maintain that although this may be the case for simple characters that are lost in evolution, the same argument does not necessarily apply to complex suites of elements such as the laterosensory system and associated structures. Under these circumstances, character losses may instead leave unique and phylogenetically recoverable patterns in the remaining elements (e.g. Weitzman & Fink, 1983: 354). Based on these premises, we regard reductive character hypotheses in Hypopygus to be fully testable on the basis of topology and connectivity (see ‘Character description and analysis’). Loss and reduction of elements of the laterosensory canal system represent 16 of the 22 reductive characters in Hypopygus. Cases of miniaturization in fishes of the order Characiformes generally appear to involve a more diverse set of bones than in Hypopygus (e.g. Characidiinae and Lepidarchus, Buckup, 1993; Zanata & Vari, 2005). Nonetheless, the extent to which the same reductive features may occur in most


HYPOPYGUS: PHYLOGENY AND TAXONOMIC REVISION other groups of miniaturized fishes is still poorly known (Schaefer et al., 1989). The derived characters present in Hypopygus species match the reductive morphological characteristics associated with miniaturization in distantly related members of Ostariophysi (Weitzman & Fink, 1985; Weitzman & Vari, 1988; Schaefer et al., 1989; Buckup, 1993; Zanata & Vari, 2005; de Pinna, Ferraris & Vari, 2007). These include the low number of anal-fin rays (character 41), the reduction or loss of body scales (characters 42 and 43), the reduction or loss of cranial bones (characters 22 and 23), and the reduction or total loss of parts of the laterosensory canal system (characters 3, 6, 7, 8, 9, 13, 14, 15, 16, 17, 18, 25, 26, 38, 39, and 46). The loss of the posterior nares (character 2) is apparently a unique and extreme case of morphological reduction, hitherto never observed in the Ostariophysi. In conclusion, based on the presence of a suite of reductive characters and reduced body size relative to outgroups, we recognize species of Hypopygus as miniaturized fishes. We also note that although Hypopygus exceed the maximum TL suggested for recognizing miniature fishes (sensu Weitzman & Vari, 1988), the use of the metric ‘length to the end of body cavity’ (Table 3) more readily qualifies these elongated fishes as miniature. Our findings add to Schaefer et al.’s (1989) general hypothesis that reductive characters have evolved on multiple independent occasions in Neotropical fishes, by convergent evolution.

TAXONOMIC ACCOUNTS HYPOPYGUS HOEDEMAN Tateichthys La Monte, 1929: 1–3 [in part, see Nijssen & Isbrücker, 1972]. Hypopygus Hoedeman, 1962: 99, fig. 4 [type species by original monotype, Hypopygus lepturus]. – MagoLeccia, 1994: 50. – Albert & Crampton, 2003: 595. Stegostenopos Triques, 1997: 2, fig. 5 [type species by monotype and original designation, Stegostenopos cryptogenes]. – Campos-da-Paz, 2007: 123 [distribution in check list; Brazil]. – Albert & Crampton, 2003: 596 [in listing of taxa]. Diagnosis: Proposed synapomorphies for Hypopygus were discussed under the synapomorphy list for the genus. Although these characters serve to delimit the genus as monophyletic, they mostly involve internal characters and are thus inappropriate for the purpose of determining whether whole specimens at hand are members of Hypopygus. Species of Hypopygus can be more readily distinguished from other gymnotiform genera, including all Rhamphichthyoidea, by the absence of the

1121

posterior nares and by the presence of a postpectoral accessory EO with dorsal and ventral anteriorprojecting grooves (See Fig. 15). Common features of species of Hypopygus: Hypopygus share a distinctive bauplan, and most species are delimited by a combination of meristic and morphometric characters and/or pigmentation, rather than major changes in external head and/or body morphology. For brevity, we describe external features common to all species of Hypopygus in this section rather than reiterating them in each species description. Conditions of the intragenerically variable external features for each species are detailed in each species account. Body elongate and laterally compressed, more so posterior to abdominal region. As with other gymnotiforms, coelomic cavity is confined to a restricted area posterior to the head, extending no more than two head-lengths posterior to occiput. Viscera rotated so that anus is positioned below operculum, adjacent to isthmus. Greatest body depth located in area of abdominal cavity or slightly posterior to abdominal cavity. Dorsal profile of body straight or nearly straight. Head widest in opercular region and deepest at nape. Eyes small, laterally positioned on dorsal half of head, and completely covered by thin membrane. Anterior nares circular, located at upper lip. Snout short. Branchial opening constricted to short vertical aperture situated along posterior margin of opercle and slightly anterior to vertical through pectoral-fin origin. Branchial membranes joined at isthmus. Anus and urogenital papilla adjacent and ventrally positioned. Mouth small and terminal, upper and lower jaws approximately equal, or upper jaw slightly longer than lower jaw. Scales cycloid, small, and present over all (or nearly all) of body, from rear of head to caudal filament. Scales absent in some species along mid-dorsal line of body. Anterior-most perforated lateral line scale located at vertical through pectoral-fin origin. Lateral line discontinuous. A postpectoral accessory EO present. Pectoral fin short to moderate, broad and distally pointed. Anal fin elongate and extending from under end of pectoral fin posteriorly for 45 to 76% of TL. Caudal filament moderate to long (21–81% of length to end of anal fin in intact specimens). Dorsal, pelvic, and caudal fins absent. Distribution: Species of Hypopygus are known to occur in most major river systems of the Amazon and Orinoco basins, from several coastal drainages of the Guianas, and from some northerly tributaries of the Rio Paraguay drainage in Brazil.


1122


KEY

TO ADULTS OF

HYPOPYGUS

SPECIES

1a. Absence of sixth infraorbital bone (Fig. 4); total number of anal-fin rays 102–135........................................2 1b. Presence of sixth infraorbital bone, as a narrow tube, positioned vertically, parallel to posterior border of eye (Fig. 3); total number of anal-fin rays 136–174 ...................................................................................... 4 2a. Presence of dark oblique stripes on lateral and dorsal portions of body; presence of scales on mid-dorsal region of body...............................................................................................................................................3 2b. Absence of dark oblique stripes on lateral and dorsal portions of body; absence of scales on mid-dorsal region of body ................................................................................................................................................ ...........Hypopygus minissimus sp. nov. (Upper Orinoco, Venezuela; Upper Rio Negro, Amazon basin, Brazil). 3a. Caudal filament long, 48.4–80.9% of length to end of anal-fin (LEA); light oblique bands present along entire body ......................Hypopygus lepturus (Wide distribution embracing: most of the Amazon basin in Bolivia, Brazil, Colombia, Ecuador, and Peru; the Orinoco basin in Colombia and Venezuela; major drainages of the Guianas in French Guiana, Guyana, and Suriname; and some northern tributaries of the Paraguay basin in Brazil.) 3b. Caudal filament short, 31.1–48.1% of LEA; light oblique bands usually restricted to below lateral line at posterior portion of body .................................................................................................................................. .......Hypopygus hoedemani sp. nov. (Widespread in Rio Negro and Rio Preto da Eva, Amazon basin, Brazil.) 4a. Presence of scattered chromatophores on anal-fin rays and membranes ..................................................... 5 4b. Absence of scattered chromatophores on anal-fin rays and membranes ...................................................... 6 5a. Snout bulbous; 137–145 anal-fin rays; 10–11 pectoral-fin rays.................................................................... ............................................................................................................................Hypopygus neblinae (Widespread in Río Orinoco, Venezuela; widespread in Rio Negro and Rio Preto da Eva, Amazon basin, Brazil.) 5b. Snout slight curved; 155–174 anal-fin rays; 14 pectoral-fin rays ................................................................. ............... Hypopygus cryptogenes (Lower and middle Rio Negro, and Rio Preto da Eva, Amazon basin, Brazil.) 6a. Bulbous head in a dorsal view; dorsal rami of intermittent branch of anterior lateral line nerve invisible......... ........................................................................................................................... Hypopygus ortegai sp. nov. (Known only from localities near Iquitos and Jenaro Herrera, Loreto, upper Amazon basin, Peru.) 6b. Triangular head in a dorsal view; dorsal rami of intermittent branch of anterior lateral line nerve visible as two black parallel lines ........................................................................................................................... 7 7a. Seven to eight scales above lateral line.................................................................................................. ..Hypopygus nijsseni sp. nov. (Known only from localities near Tefé, Amazonas, upper Amazon basin, Brazil.) 7b. Five to six scales above lateral line....................................................................................................... .......................................................................................................................................Hypopygus isbruckeri sp. nov. (Known only from near San Fernando de Atabapo, upper Orinoco basin, Venezuela.)

HYPOPYGUS CRYPTOGENES (TRIQUES) (FIG. 16; TABLE 4) Stegostenopos cryptogenes (Triques, 1997): 3, fig. 5 [original description; Brazil, Amazon basin, Igarapé Sirinau, right margin of the Rio Cuieiras, c. 25 km from its mouth on Rio Negro, approximately 2°70′S, 60°40′W]. – Albert & Crampton 2003: 496 [Amazon basin]. – Campos-da-Paz, 2007: 123 [distribution in check list; Brazil].

Diagnosis: Hypopygus cryptogenes is diagnosed from congeners by the following combination of characters: the total number of pectoral-fin rays (14 versus 9–12 in congeners, except for H. isbruckeri), the total number of anal-fin rays (155–174 versus 102–150 in congeners, except for H. isbruckeri), the head length (10.3–12.1% of LEA versus 12.2–22.9 in congeners, except for H. lepturus), the presence of the sixth infraorbital bone (versus absence in H. hoedemani, H. lepturus, and H. minissimus), the snout length

(28.9–33.3% of HL versus 18.3–28.3 in H. neblinae and H. nijsseni and 52.8–57.9 in H. ortegai), the presence of dark oblique bands (versus absence in H. minissimus), the presence of scales at midbody (versus absence in H. minissimus), and the dorsal rami of the intermittent branch of the anterior lateral line nerve visible as two black parallel lines (versus not visible in H. ortegai). Description: Head and body shape, and pigmentation illustrated in Figure 16. Morphometric data for examined specimens are presented in Table 4. Body size moderate, maximum examined TL 150 mm (N = 80). Maximum examined length from snout to end of BC 23.5 mm. No sexual dimorphism in body or head shape. Snout slightly convex. Upper jaw slightly longer than lower jaw. Pectoral-fin rays 12–16 [14] (N = 11). Postpectoral EO with two columns and four to six rows of electrocytes, its dorsal groove extending anteriorly to approximately 0.5 orbital diameters behind posterior border of eye. Scales



1123

Rio Cuieiras, a tributary of the lower Rio Negro. This river is characterized by low conductivity (< 15 mScm-1) blackwater.

Figure 16. Hypopygus cryptogenes, holotype, head, and lateral and dorsal views of body, 150 mm, MZUSP 47985; Brazil, Amazonas, Rio Negro, Rio Cuieiras. Scale bars = 5 mm.

present on mid-dorsal region of body. Scales above lateral line at midbody 5–8 [5] (N = 11). Scales below lateral line 5–7 [5] (N = 11). Total anal-fin rays 148– 174 [170] (N = 11). Caudal filament elongate. Precaudal vertebrae 14 (11 anterior; 3 transitional; N = 4). Pigmentation (Fig. 16): Head and body background light to dark brown. Dark oblique bands from nape to end of caudal filament. Fourteen to 21 light bands along lateral portion of body, counted from nape to last anal-fin ray. Bands fused at dorsal region of body. Pectoral-fin ray and inter-radial membrane hyaline or sporadically speckled with dark chromatophores. Anal-fin ray and inter-radial membrane speckled with dark chromatophores in individuals above 75 mm, and hyaline in specimens below 75 mm. Electric organ discharge: Data available only from a single EOD recording (courtesy of C. Aadland, Instituto Nacional de Pesquisas da Amazônia), recorded from the Lower Rio Negro near the area of the type locality (Fig. 17). EOD tetraphasic; duration 1.3 ms; peak power frequency 2.53 kHz; resting day-time pulse repetition rate 66 Hz. Distribution: Hypopygus cryptogenes is known from small terra firme streams and rivers in the middle and lower Rio Negro, and the Rio Preto da Eva, Amazon basin, Brazil (Fig. 18). Ecology: Triques (1997) reported that H. cryptogenes was collected together with H. lepturus in the

Material examined: (80 specimens.) Brazil. Amazonas. BMNH 1985.6.22.53–58, 6, 40–73 mm, Tarumazinho River (= Igarapé Tarumã Mirim), near Manaus, Rio Negro drainage, 02°53′47″S, 060°13′52″W. INPA 4386, 2, 57.1–71.2 mm; Rio Cuieiras, Rio Negro drainage. INPA 26254, 14, 43.3– 65.9 mm; Igarapé Tarumã-Mirim, near Manaus, Rio Negro drainage, 02°53′47″S, 060°13′52″W. INPA 29355, 1, 91.8 mm; Igarapé Tiaracá, Parque Nacional do Jaú, municipality of Nova Airão, Rio Negro drainage, 01°46′09″S, 061°38′24″W. INPA 29373, 1, 99.4 mm (CS); Igarapé Tiaracá, Parque Nacional do Jaú, municipality of Nova Airão, Rio Negro drainage, 01°48′06″S, 061°38′24″W. INPA 29412, 2 (out of 4) 50–70 mm; Igarapé Tiaracá, Parque Nacional do Jaú, municipality of Nova Airão, Rio Negro drainage, 01°48′09″S, 061°37′40″W. INPA 29446, 2, 96.0– 99.1 mm; Igarapé Tiaracá, Parque Nacional do Jaú, municipality of Nova Airão, Rio Negro drainage, 01°47′31″S, 061°37′37″W. INPA 29474, 1, 124.6 mm; Igarapé Tiaracá, Parque Nacional do Jaú, municipality of Nova Airão, Rio Negro drainage, 01°49′11″S, 061°38′24″W. INPA 30378, 1, 72.1 mm; Igarapé Toari, Rio Preto da Eva, Rio Preto da Eva drainage, 02°47′35″S, 059°38′21″W. INPA 30474, 1, 103.2 mm; Parque Estadual do Rio Negro, parest-setor Sul, Rio Negro drainage, 02°42′46″S, 060°28′20″W. INPA 30572, 1, 80 mm; Rio Igarapé Toari, Rio Preto da Eva, Rio Preto da Eva drainage, 02.7930000°S, 059.6391700°W. INPA 30650, 1, 61.9 mm; Rio Preto da Eva, Rio Preto da Eva drainage, 02°44′27″S, 059°26′48″W. MZUSP 24961, 1, 120 mm (CS); Rio Cuieiras, Rio Negro drainage, 02°50′S, 060°30′W. MZUSP 30088, 1, 147 mm (CS); Rosa Maria, Rio Negro, Rio Negro drainage, 00°19′S, 065°7′W. MZUSP 47985, holotype, 150 mm; Igarapé Sirinau, right margin of the Rio Cuieiras, c. 25 km from its mouth, Rio Negro drainage, 02°70′S, 060°40′W. MZUSP 30168, 1, 70 mm; Lago Central da Ilha de Buiu-Açu, near Rio Urubaxi, Rio Negro drainage, 00°31′S, 064°50′W. MZUSP 55103, 8, 21–64 mm; MZUSP 58998, 6, 49–89 mm; Igarapé São João, near Santa Isabel do Rio Negro (Tapurucuara), 00°24′S, 065°02′W. MZUSP 62744, 1, 75 mm; MZUSP 74277 (part), 21, 14–66 mm; Igarapé Jaradá, branch of the right margin of the Rio Cuieiras, approximately 40 km from the mouth. MZUSP 74299 (part), 1, 48 mm; Igarapé Sirinau, right margin of the Rio Cuieiras, c. 25 km from its mouth, Rio Negro drainage, 02°42′S, 060°20′W. MZUSP 95282, 1, 68 mm; unnamed stream on left margin of Rio Cuieiras, c. 20 km from its mouth, 03°00′S, 060°11′W. USNM 300957 (part), 3, 48–67 mm; unspecified


– – – – 50.3 8.2 13.2 56.4 65.8 11.6 10.1 43.2 34.9 17.9 46.8 11 63 27 11.4

(N = 15) (N = 15) (N = 15) (N = 15) (N = 15) (N = 15) (N = 15) (N = 15) (N = 15) (N = 15) (N = 15) (N = 15) (N = 15) (N = 15) (N = 15) (N = 15) (N = 15) (N = 15)

48.3–52 8.8–9.7 10.5–16.5 44.3–67.4 59.5–72.9 10.3–12.1 7.8–11.1 40–47.3 30.4–41.7 15–21.1 41.5–52.9 9.4–13 60.4–67.3 21.9–29.8 7.8–15.3 (N = 15)

Mean

57.1–150 42–94 21–56 6–9.9

Range

6.6

62.6 41.4 31.2 49.6 11.1 57.9 29.4

54 12.3 12.4 46.2 36 15.7 12.5

75 52 22.6 8

H

(N = 20) (N = 20) (N = 20) (N = 20) (N = 20) (N = 20) (N = 20)

(N = 20) (N = 20) (N = 20) (N = 20) (N = 19) (N = 20) (N = 20)

(N = 20) (N = 20) (N = 19) (N = 20)

2.9–6.8 (N = 19)

53.9–92.3 44.1–65.6 29.6–63.3 40.8–69.6 9.7–14.5 55.2–64.4 27.2–35.4

53.5–59.5 8.7–12.8 12.4–17.6 45.1–61.4 31.1–48.1 14.6–17.7 10.9–17.1

35.2–75 30–52 10–22.6 5.2–8

Range

H. hoedemani

5.3

72.3 54.8 38.8 53.3 10.2 57.5 29.7

55.9 11.4 13.7 45.6 42 15.8 15.3

– – – –

Mean

3.5

58.3 44.7 31.8 49.7 15.2 61 24.2

76 10.9 10.1 40.2 44.9 17.2 13.7

90 66 26.3 8.7

H

Number of specimens indicated in parentheses. H, holotype; range includes holotypes, paratypes, or nontype specimens.

Total length 150 Length to end of anal fin 94 Caudal filament length 56 Head length 9.6 Per cent of length to end of anal fin Anal fin length 49.1 Anus to anal-fin base 9.7 Body depth at anal-fin origin 12.4 Body width at anal-fin origin 47.4 Caudal filament length 72.9 Head length 12.1 Snout to occiput 11.1 Per cent of head length Head depth at eye 40.1 Head width at eye 41.7 Interocular width 21.1 Pectoral fin length 52.9 Orbital diameter 9.7 Postorbital length 65.5 Snout length 21.9 Per cent of caudal filament Caudal filament depth 15.3

H

H. cryptogenes

(N = 15) (N = 15) (N = 15) (N = 15) (N = 15) (N = 15) (N = 15)

(N = 14) (N = 14) (N = 14) (N = 14) (N = 14) (N = 14) (N = 14)

(N = 9) (N = 8) (N = 6) (N = 9)

2.8–3.8 (N = 13)

51.9–89.1 41.8–67.8 30.3–33.7 49.7–68.3 14.2–16 57.8–63.4 22.2–29.5

54.2–76 6.6–11.9 11.2–21 38.7–62.1 39.9–47.4 13.2–22.9 10.8–18.9

56.6–90 31.9–66 19.6–26.3 7.3–8.7

Range

H. isbruckeri

3.1

64.9 45.2 32.3 54.9 15.1 62.9 25.2

70.8 10.7 11.9 43.3 42.9 14.7 15.2

– – – –

Mean

(N = 30) (N = 30) (N = 30) (N = 30) (N = 30) (N = 30) (N = 30)

(N = 30) (N = 30) (N = 30) (N = 30) (N = 29) (N = 30) (N = 30)

(N = 30) (N = 30) (N = 29) (N = 30)

1.7–4.5 (N = 30)

58.1–85.4 41.5–73.7 18.7–24.4 53–74.8 10.9–16.3 54.2–73.1 27–40

41.2–65.1 9.6–14.2 11.1–19.3 36.2–54.3 48.4–80.9 11.1–15.3 8.7–18.4

56–116 35–66 19–44 4.9–7.8

Range

H. lepturus

Table 4. Morphometrics for examined specimens of Hypopygus cryptogenes, Hypopygus hoedemani, Hypopygus isbruckeri, and Hypopygus lepturus

3.5

59.2 55.8 21.7 54.2 13.7 63.4 35.2

50.3 13.6 12.5 45.7 57.1 12 9.9

– – – –

Mean

1124 C. D. DE SANTANA and W. G. R. CRAMPTON



1125

1

Figure 18. Map of northern South America showing collection records of Hypopygus cryptogenes. Some symbols represent more than one nearby collecting locality.

location in Rio Unini drainage, Rio Negro drainage (Rio Unini mouth = 01°40′20″S, 061°30′52″W). USNM 304973, 2, 58–62 mm; Urubaxi, Rio Negro, Rio Negro drainage, c. 00°34′S, 064°50′W.

HYPOPYGUS HOEDEMANI SP. (FIG. 19; TABLE 4)

NOV.

Hypopygus sp. Lima et al. 2005: 260 [first illustration; Rio Tiquié, Amazon basin].

Figure 17. Electric organ discharges (EODs) of Hypopygus as time-voltage waveforms recorded in the far-field. The EODs were in all cases taken from immature specimens or females with adult morphology, and are representative of most individuals of each species (small juveniles and sexually mature males present EODs that in some cases differ from those of larger juveniles, immature adults, and females). A, Hypopygus cryptogenes, INPA uncatalogued, 80 mm (poor signal recording quality). B, Hypopygus isbruckeri, UF 148537 (WC38.150304), immature, 76 mm. C, Hypopygus lepturus, UF 176883 (WC21.090307), female, 92 mm. D, Hypopygus minissimus, UF 148533 (WC41.120304), female, 42 mm. E, Hypopygus neblinae, UF 148540 (WC36.150304), female, 77 mm. F, Hypopygus nijsseni MCP 44740 (WC01.070703), immature, 70 mm. G, Hypopygus ortegai, MUSM 35305, holotype (WC02.160104), female, 107 mm. Scale bars = 1 ms. Dashed horizontal line = 0 volts. Note that all species generate EODs with a similar four- or five-phase structure, with minimal interspecific variation in duration (except in H. neblinae where the EOD is clearly longer).

Diagnosis: Hypopygus hoedemani is diagnosed from congeners by the following combination of characters: the absence of the sixth infraorbital bone (versus presence in all congeners except H. lepturus and H. minissimus), the total number of anal-fin rays (102–118 versus 136–174 in all congeners, except for H. lepturus and H. minissimus), the length of the caudal filament (31.1–48.1% of LEA versus 48.4–80.9 in H. lepturus), the presence of oblique bands (versus absence in H. minissimus), the presence of scales at midbody (versus absence in H. minissimus), and the dorsal rami of intermittent branch of anterior lateral line nerve visible as two black parallel lines (versus not visible in H. ortegai). Description: Head and body shape, and pigmentation illustrated in Figure 19. Morphometric data for examined specimens are presented in Table 4. Body size small, maximum examined TL 75 mm (N = 22). Maximum examined length from snout to end of BC 17.8 mm. No sexual dimorphism in body or head shape. Snout slightly convex. Upper and lower jaws approximately equal in length. Pectoral-fin rays 11–13 [13] (N = 17). Postpectoral EO with two columns and four to six rows of electrocytes, its dorsal groove extending anteriorly to approximately one to two orbital diameters before posterior border of eye. Scales present on mid-dorsal region of body. Scales above lateral line at midbody 5–8 [8] (N = 17). Scales below lateral line 4–6 [4] (N = 4). Total anal-fin rays 102–118 [110] (N = 15). Caudal filament moderate. Precaudal vertebrae 16 [16] (12–15 anterior; 1–4 transitional; N = 4).


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C. D. DE SANTANA and W. G. R. CRAMPTON 1 2

Figure 20. Map of northern South America showing collection records of Hypopygus hoedemani (circles), and Hypopygus isbruckeri (squares). Some symbols represent more than one nearby collecting locality.

Distribution: Hypopygus hoedemani is known from small terra firme streams and rivers in the Rio Negro and Rio Preto da Eva drainages of the Amazon basin, Brazil (Fig. 20).

Figure 19. Hypopygus hoedemani, holotype, head, and lateral and dorsal views of body, 52.9 mm, INPA 30375; Brazil, Igarapé Toari, Rio Preto da Eva drainage. Scale bars = 5 mm.

Pigmentation (Fig. 19): Small specimens 40.3– 45.4 mm, and one examined individual of 59.2 mm with light to dark brown body background, pale oblique bands from nape to end of caudal, and 14 to 17 clear bands crossing dorsal region of body (counted from nape to last anal-fin ray). Remaining specimens (to 75 mm), including holotype, with light to dark brown background, pale bands restricted to postpectoral portion of body and region below lateral line, middorsal portion of body even brown – occasionally with sparse clear bands, mainly in posterior region. Head of all specimens light to dark brown, sometimes with a depigmented area ventroposterior to eye. Pectoral-fin ray and inter-radial membrane hyaline, sporadically speckled with dark chromatophores. Anal-fin rays hyaline with dark pigmentation on anterior and posterior portions of fin. Inter-radial membrane hyaline anteriorly and darkly pigmented posteriorly. Dorsal rami of intermittent branch of anterior lateral line nerve visible as two black parallel lines, on each side of upper back from approximately one to one-half pectoral fin length behind the occiput, running posteriorly to mid-dorsal portion of body. Lateral line nerve visible as dark line, extending from above pectoral fin to approximately two-thirds into caudal filament. Electric organ discharge: Unknown.

Ecology: Lima et al. (2005) presented short notes on H. hoedemani. They reported finding this species in submerged vegetation and the bed of lakes, pools, and small streams of the Rio Tiquié, a tributary of the Rio Uaupés, Rio Negro drainage. They reported that it feeds on aquatic invertebrates, including termites, insect larvae, and oligochaetes. Etymology: The specific epithet, hoedemani, is a patronym in honour of J. J. Hoedeman for his contributions to Neotropical ichthyology, including the description of H. lepturus, the type species of the genus. Remarks: The absence of extrascapular bones and the presence of two ossified mandibular canal bones (see Character description and analysis) are autapomorphies for the species. Material examined: (22 specimens.) Holotype. Brazil. Amazonas. INPA 30375, 1, 52.9 mm; Igarapé Toari, Rio Preto da Eva drainage, 02°47′35″S, 059°38′21″W; L. N. Carvalho, 11.viii.2006. Paratypes. Brazil. Amazonas. INPA 29855, 1, 56.0 mm; Rio Preto da Eva, 02.74078°S, 059.67142°W; L. N. Carvalho, 08.vi.2006. INPA 30049, 1, 28 mm; Rio Preto da Eva, Igarapé Toari, 02.74078°S, 059.67142°W; L. N. Carvalho, 04.x.2006. INPA 33948 (ex. 30375), 2, 49.4–55.4 mm (1 CS); Igarapé Toari, Rio Preto da Eva drainage, 02°47′35″S, 059°38′21″W; L. N. Carvalho, 11.viii.2006. MZUSP 30169, 3, 35.2– 53.1 mm; Rio Negro, below Rio Daraá; M. Goulding, 16.ii.1980. MZUSP 59196, 1, 45.8 mm; stream at São João, near Tapurucuara (= Santa Isabel do Rio Negro); Expedição Permanente à Amazônia, 23.x.1972. MZUSP 62744, 75.0 mm; Igarapé Jaradá, right margin of the Rio Cuieiras, c. 40 km above the mouth; Alpha Helix Amazon Expedition, 1.ii.1977. MZUSP 74277 (part), 1, 49.5 mm; Igarapé Jaradá, branch of the right



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Description: Head and body shape, and pigmentation illustrated in Figure 21. Morphometric data for examined specimens are presented in Table 4. Body size moderate, maximum examined TL 90.0 mm (N = 9). Maximum examined length from snout to end of BC 20 mm. Snout slightly convex. Upper and lower jaws approximately equal in length. Pectoral-fin rays 12–16 [14] (N = 9). Postpectoral EO with two columns and five to seven rows of electrocytes, its dorsal groove extending anteriorly to approximately one and a half to two orbital diameters behind posterior border of eye. Scales present on mid-dorsal region of body. Scales above lateral line at midbody 7–8 [8] (N = 9). Scales below lateral line 5–7 [7] (N = 4). Total anal-fin rays 136–152 [150] (N = 9). Caudal filament moderate. Precaudal vertebrae 14 (11–12 anterior; 2–3 transitional; N = 3). Figure 21. Hypopygus isbruckeri, holotype, head, and lateral and dorsal views of body, UF 148539, 90 mm, immature; Venezuela, Amazonas, stream at Caño Magua, approximately 1 km from Magua, 13 km from San Fernando de Atabapo, 3°58′50.22″N, 67°36′28.08″W. Scale bars = 5 mm. Note. Scales are missing along mid section of flank because of specimen damage.

Pigmentation (Fig. 21): Head and body background coloration light brown. Eighteen to 20 dark stripes on dorsal region. Dorsal rami of intermittent branch of anterior lateral line nerve visible as two black parallel lines, on each side of upper back from approximately one to one-half pectoral fin length behind the occiput, running posteriorly to mid-dorsal portion of body.

margin of the Rio Cuieiras, c. 40 km of the mouth; Alpha Helix Amazon Expedition, 31.i.1977. MZUSP 74299 (part), 3, 50.4–62.9 mm; Igarapé Sirinau, right margin of the Rio Cuieiras, c. 25 km from the mouth, Rio Negro drainage, 02°42′S, 060°20′W; Alpha Helix Amazon Expedition, 30.i.1977. MZUSP 81488, 8, 40.3–65.1 mm (1CS); Rio Tiquié, Igarapé Mipiriyapotemakãya, branch of Igarapé Açaí, 00°15′55″N, 069°58′16″W; F. Lima et al., 29.x.2002.

Electric organ discharge: Data available only from a single specimen, UF 148537 (WC38.150304, 76 mm, immature). EOD tetraphasic (Fig. 17); duration 1.26 ms; peak power frequency 2.23 kHz; day-time pulse repetition rate 46.2 Hz (1 min recording: range 44.2–56.1 Hz, SD 1.78 Hz).

HYPOPYGUS ISBRUCKERI SP. (FIG. 21; TABLE 4)

Distribution: Hypopygus isbruckeri is known only from the vicinity of San Fernando de Atabapo, Amazonas, Venezuela (Fig. 20).

NOV.

Diagnosis: Hypopygus isbruckeri is diagnosed from congeners by the following combination of characters: the total number of anal-fin rays (136–156 versus 102–135 in H. hoedemani, H. lepturus, and H. minissimus), the presence of the sixth infraorbital bone (versus absence in H. hoedemani, H. lepturus, and H. minissimus), the presence of oblique bands (versus absence in H. minissimus), the presence of scales at midbody (versus absence in H. minissimus), the total number of pectoral fin rays (12–16 versus 10–12 in H. nijsseni), the number of scales above the lateral line (seven to eight versus five to six in H. nijsseni, and three to five in H. neblinae), the head length (13.2–22.9% of LEA versus 12.6–13.9 in H. ortegai), and the dorsal rami of intermittent branch of anterior lateral line nerve visible as two black parallel lines (versus not visible in H. ortegai).

Ecology: Hypopygus isbruckeri is known from small rainforest and savannah streams, in marginal root mats, leaf litter, and aquatic vegetation. In the region of the type locality it is apparently uncommon. It occurs in sympatry and ecological syntopy with three congeners: H. lepturus (uncommon), H. minissimus (uncommon), and H. neblinae (common). Stomach contents include Chironomidae larvae and other small aquatic insect larvae. Etymology: The specific epithet, isbruckeri, is a patronym in honour of I. J. H. Isbrücker for his contributions to Neotropical ichthyology, including Hypopygus (Nijssen & Isbrücker, 1972). Material examined: (Nine specimens.) Holotype. Venezuela. Amazonas. UF 175390, 90.0 mm, immature; Caño Magua, forest stream approximately


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1 km from Magua, 13 km and 126° from San Fernando de Atabapo, Río Orinoco drainage, 03°58′50.2″N, 067°36′28.1″W; W. Crampton et al., 11–15.iii.2004. Paratypes. Venezuela. Amazonas. UF 148537, 2, 56.6–75.2 mm (1 recorded: WC38.150304, immature, 75.2 mm); Caño Viejita, moriche palm swamp in savannah, road from San Fernando de Atabapo to Santa Bárbara, 16.5 km and 142° from San Fernando de Atabapo, 03°55′59.0″N, 067°36′34.2″W; W. Crampton et al., 12–15.iii.2004 UF 148539, 6 (3 CS), 50.0– 90.0 mm; same collecting data as holotype.

HYPOPYGUS LEPTURUS HOEDEMAN (FIGS 22, 23A; TABLE 4) Hypopygus lepturus Hoedeman, 1962: 99, fig. 4 [original description; ‘Maroni basin, no exact locality’, Suriname, holotype RMNH 19466, 74 mm]. – Nijssen & Isbrücker, 1972: 162, [type locality by restriction:

Figure 22. Hypopygus lepturus, nontype, head, and lateral and dorsal views of body, UF 176882 (WC07.050307), male, 97.5 mm; Suriname, Kola Kreek, c. 6 km west of Zanderij, Para Rivier drainage. 05°27′08″N, 055°14′42″W. Scale bars = 5 mm. 䉴 Figure 23. Live specimens of Hypopygus from the upper Amazon: A, Hypopygus lepturus, MCP 44602, immature, 78 mm; Brazil, Amazonas, Rio Tefé, Lago Tefé, Igarapé Repartimento on road from Tefé to Agrovila, 03°24′28″S, 64°44′10″W. B, Hypopygus nijsseni, MCP 44740 (WC01.070703), immature, 70 mm; Brazil, Amazonas, Ilha Martelo, Rio Tefé, 03°46′53.1″S, 64°59′57.3″W. C, Hypopygus ortegai, UF 148524 (WC01.160104), immature, 92 mm; Peru, Loreto, km 3.9 on road from Jenaro Herrera to Colonia Angamos, 04°53′01″S, 073°38′10″W. © 2011 The Linnean Society of London, Zoological Journal of the Linnean Society, 2011, 163, 1096–1156

HYPOPYGUS: PHYLOGENY AND TAXONOMIC REVISION ‘Surinam, Marowijne District, Maka Creek, at left bank of Lawa River, 10 km S. of center of Stoelman’s Island, Marowijne River system, 04°16′N, 52°25′W’ (note, the correct coordinate is 04°16′N, 54°25′W), with establishment of five topotypes, ZMA 106.082, max. 87 mm], figs 1–3; pl. 1 (photograph of holotype), pl. 2 (photograph of two topotypes). – Mago-Leccia, 1994: 50, fig. 76 [Suriname]. – Planquette, Keith & Le Bail, 1996: 395, with photograph [French Guyana]. – Albert & Crampton, 2003: 495 [Amazon basin, Orinoco basin, Suriname]. – Crampton & Albert 2006: 672, fig. 24.8 (including EOD waveform) [Amazon basin, Orinoco basin, Guianas]. – Campos da Paz, 2007: 123 [distribution in check list; Brazil]. Diagnosis: Hypopygus lepturus is diagnosed from congeners by the following combination of characters: the absence of the sixth infraorbital bone (versus presence in all congeners except H. hoedemani and H. minissimus), the total number of anal-fin rays (109–135 versus 136–170 in all congeners except H. hoedemani and H. minissimus), the length of the caudal filament (48.4–80.9% of LEA versus 31.1–48.1 in H. hoedemani), the presence of scales at midbody (versus absence in H. minissimus), the presence of oblique bands (versus absence in H. minissimus), and the dorsal rami of the intermittent branch of anterior lateral line nerve visible as two black parallel lines (versus not visible in H. ortegai). Description: Head and body shape, and pigmentation illustrated in Figures 22 and 23A. Morphometric data for examined specimens are presented in Table 4. Body size moderate, maximum examined TL 116 mm (N = 4252). Maximum examined length from snout to end of BC 19.2 mm. No sexual dimorphism in body or head shape. Snout slightly convex. Upper jaw slightly longer than lower jaw. Pectoral-fin rays nine to ten (N = 20). Postpectoral EO with two columns and four to six rows of electrocytes. EO dorsal groove extending anteriorly to approximately one to two orbital diameters behind posterior border of eye. Scales present on mid-dorsal region of body. Scales above lateral line at midbody 4–5 (N = 20). Scales below lateral line 4–6 (N = 20). Total anal-fin rays 109–135 (N = 20). Caudal filament elongate. Precaudal vertebrae 15 (12–13 anterior; two to three transitional; N = 20). Pigmentation (Figs 22, 23A for colour of live specimen): Pigmentation varies considerably amongst individuals in the same population across the entire distribution of the species (e.g. see Nijssen & Isbrücker, 1972: figs 2, 3). Head and body background light to dark brown. Eleven to 20 pale oblique bands from nape to end of caudal filament. Pectoral-fin

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1

Figure 24. Map of central and northern South America showing collection records of Hypopygus lepturus. Some symbols represent more than one nearby collecting locality.

ray and inter-radial membrane hyaline, sporadically speckled with dark chromatophores. Anal-fin ray and inter-radial membrane hyaline. Dorsal rami of intermittent branch of anterior lateral line nerve visible as two black parallel lines on each side of upper back, from approximately one to one-half pectoral fin lengths behind the occiput, running posteriorly to mid-dorsal portion of body. Lateral line nerve sometimes visible as dark line, extending from above pectoral fin to caudal filament. Electric organ discharge: Previous studies have described some aspects of the electric signals of H. lepturus – including EOD shape, and pulse rate (see Introduction). Here we summarize, for the first time, data from populations near the region of the type locality in Suriname (UF 176882–UF 176884, N = 23). Forthcoming studies will explore interpopulation variation, and interspecific variation of EODs in the Steatogenini. Hypopygus lepturus generates a tetraphasic EOD (Fig. 17); duration 0.85–1.15 ms (mean 0.97, N = 22), peak power frequency 2.502–3.359 kHz (mean 2.815, N = 22). Mean pulse rate during the day ranges from 34.5 to 71.6 Hz [mean 56.9, coefficient of variance (CV) 3.19, N = 23], and during the night from 49.0 to 85.2 Hz (mean 77.8, CV 4.60, N = 22). Distribution: Hypopygus lepturus exhibits a much wider geographical range than all other species of Hypopygus, occurring across most major drainages of the Amazon basin in Bolivia, Brazil, Colombia, Ecuador, Peru, from many drainages of the Orinoco basin in Colombia and Venezuela, from coastal drainages of the Guianas in Guyana, Suriname, and French Guiana, and from northern tributaries of the Paraguay in Brazil (Fig. 24).


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Ecology: Hypopygus lepturus is a common component of the ichthyofauna of nutrient-poor (electrical conductivity typically less than 30 mScm-1) creeks and streams throughout its range. Our observations indicate that the behaviour and ecology of this species are similar throughout its geographical range. It typically occurs in groups of several to many dozens of individuals in hanging root mats along the edge of stream banks, especially where the bank is undercut. During the day H. lepturus hide in these locations, but at night they emerge to forage in adjacent leaf litter and along the root-clad margins of streams. Hypopygus lepturus typically prefers gently flowing water (0.05– 0.25 ms-1) (although currents are typically negligible within the substrate in which it shelters) and is usually absent if there is no flow at all. Stomach contents of H. lepturus contain a variety of small autochthonous aquatic invertebrates – mostly the larvae of Chironomidae and other aquatic insects, but also some small allochthonous insects – mostly ants and termites. Throughout much of its range H. lepturus occurs without congeners. However, from our examination of museum lots, and from expeditions, we noted its syntopic co-occurrence with other Hypopygus in several areas: Iquitos and Jenaro Herrera region, Loreto, Peru (with H. ortegai); Tefé region, Amazonas, Brazil (with H. nijsseni); lower and middle Rio Negro (with H. cryptogenes, H. hoedemani, H. neblinae) upper Rio Negro (with H. hoedemani, Lima et al., 2005, H. minissimus, and H. neblinae); upper Orinoco in region of San Fernando de Atabapo (with H. isbruckeri, H. minissimus, H. neblinae). Remarks: Hypopygus lepturus is the most widespread species in the genus, and not surprisingly we found differences in the pattern of colorations and meristic ranges between distant populations. For instance we found some non-overlapping differences in the number of anal-fin rays between populations in Suriname and the Rio Negro. A detailed examination using molecular tools may ultimately be necessary to determine whether cryptic species diversity exists amongst populations identified here as H. lepturus. Material examined: (4317 specimens.) Bolivia. Beni. AMNH 39825, 11, 45–60 mm; backwater tributary of Río Itenez, 10 km SE Costa Marques (Brazil), Rio Guaporé (Mamoré), Rio Madeira drainage, 12°33′00″S, 064°12′24″W. CBF 10285, 1, 83 mm (WC09.250607, female); CBF 10286, 1, 89 mm (WC10.250607, female); CBF 10287, 1, 83 mm (WC11.250607, male); stream near Lago de San José, near Riberalta, Río Beni, Río Madeira drainage, 10°54′46″S, 065°59′49″W. CBF 10288, 1, 104 mm (WC30.270607, male); CBF 10289, 1, 101 mm (WC31.270607, male); shallow pond near Lago de San

José, near Riberalta, Río Beni, Río Madeira drainage, 10°54′46″S, 065°59′49″W. CBF 10290, 1, 93 mm (WC03.280607, immature); CBF 10291, 1, 76 mm (WC09.280607, female); CBF 10292, 1, 71 mm (WC10.280607, female); CBF 10293, 1, 56 mm (WC11.280607, immature): stream near Lago de San José, near Riberalta, Río Beni, Río Madeira drainage, 10°55′32″S, 066°00′36″W. UF 176881, 2, 48–90 mm (WC37.060707, male, 90 mm; WC38.060707, immature, 48 mm); stream on Riberalta-Guayaramerim road, near Boceron, 11°02′50″S, 065°50′06″W. UMMZ 204514, 1, 61 mm; Río Itenez and overflow pools, along middle of sandbar, 9 km SE of Costa Marques, Brazil, Río Guaporé (Rio Mamoré), Rio Madeira drainage,12°32′24″S, 064°12′42″W. UMMZ 204633, 1, 57 mm; Rio Itenez, mouth of tributary in overflow, 0.25 km above mouth of Río Baurés, 5 km SW Costa Marques, Brazil, Río Guaporé (Rio Mamoré), Rio Madeira drainage,12°30′30″S, 064°19′00″W. UMSS 7049, 1, 53 mm (WC12.280607, immature); UMSS 7050, 1, 60 mm (WC13.280607, immature); UMSS 7051, 1, 52 mm (WC14.280607, immature); UMSS 7052, 1, 56 mm (WC15.280607, female); UMSS 7053, 1, 90 mm (WC16.280607, immature); stream near Lago de San José, near Riberalta, Río Beni, Río Madeira drainage, 10°55.537′S, 066°00.60′W. UMSS 7054, 1, 77 mm (WC25.290607, female), Riberalta-Guayaramerim Road near km 43; 11°00′ 30.2″S, 065°39′49.4″W. UMSS 7055, 1, 62 mm (WC33.060707, immature); UMSS 7056, 1, 61 mm (WC34.060707, immature); UMSS 7057, 1, 65 mm (WC35.060707, immature); UMSS 7058, 1, 99 mm (WC36.060707, male); stream on RiberaltaGuayaramerim road, near Boceron, 11°02.844′S, 065°50.114′W. USNM 305589, 9, 36–54 mm; Ballivia Province, Lago Normandia, south-east portion, 40 km east of San Borja, 14°55′S, 066°18′W. Pando. FMNH 106698, 3, 25–35 mm; Río Manuri, c. 12 km upstream of Puerto Rico, Río Madeira drainage, 11.15°S, 067.56°W. Brazil. Acre. MCP 29033, 4, 44–80 mm; stream on BR-364, 39 km 147° from near Sena Madureira, Rio Purus drainage, 09°22′14″S, 068°27′21″W. Amazonas. BMNH 1998.3.11.35–43. 9, 35–43 mm (WC06.260395 immature; WC07.260395 immature; WC08.260395 immature; and six unrecorded immature); Igarapé Repartimento, 7 km and 230° from Tefé, Rio Tefé drainage, 03°24′55″S, 064°45′00″W. BMNH 1985.6.22.59–63, 5, 47–64 mm; BMNH 1985.6.22.64–68, 4 (of 5), 40–63 mm; Tarumazinho River (= Igarapé Tarumã Mirim), near Manaus, Rio Negro drainage, 02°53′47″S, 060°13′52″W. INPA 6620, 4, 42.4–53.1 mm; Santa Isabel do Rio Negro, Igarapé Santo Antônio, near Nova Esperança above Santa Isabel, Rio Negro drainage. INPA 9955, 13, 71.5–98.3 mm; Igarapé Repartimento, 4 km south-east of Tefé, municipality of Tefé, Rio Tefé


HYPOPYGUS: PHYLOGENY AND TAXONOMIC REVISION drainage, 03°24′55″S, 064°45′00″W. INPA 15829, 9, 73.1–89.6 mm (WC03.120398, male, 98 mm; WC04.120398, male, 95 mm; WC05.120398, female, 85 mm; WC08.120398, male, 102 mm; WC09.120398, female, 77 mm; WC10.120398, male, 83 mm; WC11.120398, female, 83 mm; WC12.120398, male, 82 mm; WC13.120398, male, 97 mm); Igarapé Repartimento, municipality of Tefé, Rio Tefé drainage. INPA 16027, 4, 23.4–38.2 mm; Igarapé Santo Antoninho, Rio Tarumã-Açu, near Manaus, BR-174, km 18. INPA 16159, 127, 29.1–70.5 mm; Presidente Figueiredo, Rio Uatumã, Igarapé Catitu, Rio Uatumã drainage. INPA 17140, 2, 36.4–49.5 mm; Santa Luzia, Rio Purus, Rio Purus drainage, 04°42′18″S, 062°22′25″W. INPA 17159, 10, 42–63 mm; Igarapé Das Duas Bocas, branch of Paraná do Jaú, Rio Purus drainage. INPA 18174, 1, 64.3 mm (WC04.060197, female); INPA 18427, 1, 36 mm (WC04.030899, immature); INPA 18430, 4, 63–88 mm; WC01.070200, immature, 78 mm; WC02.070200, female, 68 mm; WC13.070200, female, 63 mm; WC05.280200, female, 83 mm); INPA 18432, 3, 84–100 mm (WC11.290200, male, 100 mm; WC12.040300, female, 89 mm; WC13.040300, female, 84 mm; Rio Tefé, Lago Tefé, Igarapé Curupira, municipality of Tefé, Rio Tefé drainage. INPA 18173, 3, 78–95 mm (WC02.200197, immature, 78 mm; WC04.200197, male, 90 mm; WC07.200197, male, 95 mm); INPA 18175, 3, 66–83 mm (WC02.170297, female, 66 mm; WC04.170297, female, 81 mm; WC12.170297, male, 83 mm); INPA 18223, 1, 97.6 mm; INPA 18425, 1, 80 mm (WC06.181296, immature); INPA 18426, 1, 82 mm (WC03.201296, immature); INPA 18429, 9, 70–100 mm (WC06.010200, immature, 85 mm; WC07.010200, female, 70 mm; WC08.010200, immature, 74 mm; WC07.040200, immature, 84 mm; WC16.040200, female, 81 mm; WC24.040200, male, 100 mm; WC25.040200, female, 72 mm; WC27.040200, male, 89 mm; WC30.040200, immature, 84 mm); INPA 18431, 1, 83 mm (WC05.280200, female); INPA 18523, 1, 104 mm (WC08.250299, male); Tefé, Lago Tefé, Igarapé do Repartimento, Rio Tefé drainage. INPA 18428, 1, 58 mm (WC 01.211199, immature); Lago Amanã, mouth of Igarapé Juá Grande, municipality of Maraã, Rio Japurá drainage. INPA 21957, 1, 47.9 mm; Rio Negro, Rio Cuieiras, Fazenda Dimona (Projeto de Dinâmica Biológica de Fragmentos Florestais) INPA 26275, 4, 46.2–57.8 mm; Igarapé Tarumã-Mirim, near Manaus, Rio Negro drainage, 2°53′47″S, 60°13′52″W. INPA 27248, 1, 56.7 mm; Igarapé Munduca, affluent of left margin of Igarapé Ipixuna, near Coari, Igarapé Ipixuna drainage, 03°54′00″S, 063°56′03″W. INPA 28599, 6, 48.9– 57.3 mm; Igarapé, km 10, near Francisca Mendes, Rio Preto da Eva drainage, 02°45′16″S, 059°37′29″W. INPA 29218, 1, 59.7 mm; Lago Uauaçu, Igarapé Ilhinha, near Beruri, Rio Purus drainage. INPA 29356, 43,

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36.1–67.4 mm; Igarapé Tiaracá, Parque Nacional do Jaú, municipality of Nova Airão, Rio Negro drainage, 01°46′09″S, 061°38′22″W. INPA 29275, 3, 52.2– 57.9 mm; Lago Ayapuá, Igarapé Ajará, municipality of Beruri, Rio Purus drainage, 04°25′07″N, 062°15′36″W. INPA 29412, 2 (of 4), 50–60 mm; Igarapé Tiaracá, Parque Nacional do Jaú, municipality of Nova Airão, Rio Negro drainage, 01°48′09″S, 061°37′36″W. INPA 29388, 4, 54.9–61.6 mm; Igarapé Tiaracá, Parque Nacional do Jaú, municipality of Nova Airão, Rio Negro drainage, 01°45′30″S, 061°37′37″W. INPA 29447, 22, 42.1–76.5 mm; Igarapé Tiaracá, Parque Nacional do Jaú, municipality of Nova Airão, Rio Negro drainage, 01°45′30″S, 061°37′37″W. INPA 29374, 22, 44.1–82.8 mm; Igarapé Tiaracá, Parque Nacional do Jaú, municipality of Nova Airão, Rio Negro drainage, 1.8016700°S, 061.6462800°W. INPA 29475, 78, 40.9–91.0 mm; Igarapé Tiaracá, Parque Nacional do Jaú, municipality of Nova Airão, Rio Negro drainage, 01°46′11″S, 061°38′24″W. INPA 29823, 2, 71.6–97.4 mm; INPA 29824, 1, 75.8 mm; PDBFF/km 37, near Manaus, Rio Urubu drainage, 02°24′53″S, 059°46′23″W. INPA 29928, 1, 68.6 mm; PDBFF/km 37, near Manaus, Rio Urubu drainage, 02°24′46″S, 059°46′27″W. INPA 29995, 1 (no size data); PDBFF/Cabo Frio, Rio Urubu drainage, 02°24′24″S, 059°53′42″W. INPA 29958, 6, 35.6–59.7 mm; INPA 30250, 8, 13.3–85.2 mm; Igarapé Ajuricaba, municipality of Presidente Figueredo, Rio Urubu drainage, 02°07′04″S, 051°56′06″W. INPA 30030, 5 (no size data); Igarapé Toari, Rio Preto da Eva drainage, 02°47′35″S, 059°38′21″W. INPA 30084, 3, 26.9–45.2 mm; Rio Cuieiras, PDBFF/DIMONA, Rio Negro drainage, 02°12′43″S, 060°03′19″W. INPA 30295, 1, 38.3 mm; Igarapé Ajuricaba, municipality of Presidente Figueiredo, Rio Urubu drainage, 02°07′04″S, 051°56′06″W. INPA 30384, 6, 67.7–74.0 mm; Igarapé Toari, Rio Preto da Eva drainage, 02°47′35″S, 059°38′21″W. INPA 30487, 8, 65.8–94.2 mm; Igarapé Tucumã, Parque Estadual do Rio Negro, near Manaus, Rio Negro drainage, 02°42′46″S, 060°28′20″W. INPA 30527, 6, 67.9–75.2 mm; Rio Cuieiras, PDBFF/ DIMONA, Rio Negro drainage, 02°20′29″S, 060°06′09″W. INPA 30586, 23, 19.9–49.9 mm; Rio Preto da Eva drainage, 02°47′35″S, 059°38′21″W. INPA 30686, 1 (no size data); Rio Carabinani, above Cachoeira, municipality of Novo Airão, 02°01′58″S, 061°32′47″W. INPA 30736, 1, 89 mm; Manaus, Rio Branquinho, Rio Cuieiras, Rio Negro drainage, 02°32′10″S, 060°19′33″W. INPA 31995, 2, 68.0– 7.4 mm; Itacoatiara, Mil Madeira Ltda., Rio Urubu drainage, 02°48′15″S, 058°52′15″W. MCP 33344, 1, 59 mm; Boca do Igarapé Juá Grande, Lago Amanã, municipality of Maraã, Rio Japurá drainage, 02°26′53″S, 064°47′34″W. MCP 33345, 2, 82–94 mm; MCP 44745, 4, 70–92 mm (4 recorded: WC01.181296,


1132


immature, 92 mm; WC05.181296, immature, 70 mm; WC04.291296, immature, 83 mm; WC01.290197, male, 95 mm); MCP 44746, 5, 70–96 mm (5 recordings: WC03.200197, female, 73 mm; WC05.200197, male, 93 mm; WC06.200197, male, 96 mm; WC08.200197, female, 76 mm; WC08.200197, immature, 70 mm); MCP 44752, 1, 95 mm (WC09.070200, male); Igarapé Curupira, near bridge on Tefé-Agrovila highway, 9.7 km and 199° from Tefé, municipality of Tefé, Lago Tefé, Rio Tefé drainage, 03°26′01″S, 064°43′47″W. MCP 33346, 1, 84 mm; MCP 33347, 1, 90 mm; MCP 44747, 5, 74–95 mm (4 recordings: WC05.170297, male, 96 mm; WC06.170297, female, 78 mm; WC10.170297, male, 91 mm; WC11.170297, male, 88 mm; WC02.260297, male, 95 mm); MCP 44749, 1, 87 mm (WC01.301298, female); MCP 44599, 1, 81 mm (1 CS) (WC05.221299, immature); MCP 44600, 7, 64–100 mm (1 CS) (7 recorded: WC02.290100, female, 73 mm; WC05.010200, female, 84 mm; WC10.040200; female, 64 mm (CS); WC17.040200, female, 79 mm; WC26.040200, male, 92 mm; WC28.040200, male, 90 mm; WC29.040200, male, 100 mm); MCP 44601, 4, 42–104 mm (3 recordings: WC01.290500, immature, 42 mm; WC07.110300, male, 98 mm; WC05.270300, male, 104 mm); MCP 44753, 1, 106 mm (WC01.100600, immature); MCP 44602, 2, 78–78 mm; MCP 44652, 1, 98 mm (WC05.210201, male, 98 mm); Igarapé Repartimento, 1.5 km downstream Estrada Agrovila, c. 7 km and 230° from Tefé, municipality of Tefé, 03°24′30″S, 064°59′29″W. MCP 44748, 3, 68–74 mm (1CS) (3 recorded: WC18.031298, female, 74 mm (CS); WC19.031298, immature, 68 mm; WC20.031298, immature, 73 mm); MCP 44750, 1 (WC02.211299, immature, 59 mm); Boca do Igarapé Juá Grande, Lago Amanã, municipality of Maraã, Rio Japurá drainage, 03°26′53″S, 064°59′29″W. MCP 44751, 1 (WC02.060100, male, 81 mm); Ilha do Martelo, Rio Tefé, 57 km and 214° from Tefé, municipality of Tefé, Rio Tefé drainage, 03°46′49″S, 064°59′29″W. MCP 44754, 1, 89 mm; small unnamed stream draining directly into Rio Solimões, on road from Nogueira to Alvarães, 3.9 km and 221° from Alvarães, Municipality of Alvarães, Rio Solimões drainage, 03°14′16″S, 064°49′42″W. MCP 44755, 3, 30.0–46.5 mm (3CS), Igarapé Baré, tributary of Lago Amanã, municipality of Maraã, Rio Japurá drainage, 02°26′17″S, 064°43′30″W. MCZ 52605, 1, 58 mm; small inlet in a branch of small river flowing from west into Rio Cuieiras, Rio Negro drainage, 02°50′S, 060°35′W. MCZ 78162, 2, 58–67 mm; Reserva Ducke near Manaus, Rio Preto da Eva drainage, 02°58′S, 059°55′W. MCZ 9455, 1, 38 mm; ‘Silva, Lago Saraca’ (= Lago Saracá at Silves), 02°53′S, 58°21′W. MCZ 9464, 1, 59 mm; ‘Cudajas’ (= Codajás, Rio Solimões), 03°55′S, 062°12′W. MPEG 965, 1, 35 mm; Vista Escura, Rio Tefé, municipality of Tefé, Rio Tefé drainage,

c. 02°51′S, 065°01′W. MPEG 966, 2, 24–35 mm, Lago Jurupari, Rio Tefé, municipality of Tefé, Rio Tefé drainage, c. 02°51′S, 065°01′W. MPEG 1095, 4, 47–55 mm; Manaus-Caracaraí highway, near bridge over Rio Branco, Rio Negro drainage, 01°44′24″N, 061°08′35″W. MPEG 1096, 1, 60 mm; MPEG 1099 (part), 5, 35–57 mm; MPEG 1109, 1, 41 mm; Anavilhanas archipelago of Rio Negro, municipality of Novo Airão, Rio Negro drainage, c. 02°44′S, 060°40′W. MPEG 1101 (part), 8, 35–67 mm; Igarapé Tarumã Grande, municipality of Manaus, c. 02°55′S, 060°06′W, Rio Negro drainage. MPEG 11756, 1, 57 mm; MPEG 11760, 6, 55–62 mm; Igarapé Lontra, municipality of Coari, Rio Urucu drainage, 04°52′5.52″S, 065°07′26.4″W; MPEG 13105, 2, 75–80 mm; Igarapé Lontra, municipality of Coari, Rio Urucu drainage, 04°49′29″S, 065°01′50.16″W. MZUSP 6639, 11, 43–66 mm; stream of Lago Manacapuru, municipality of Manacapuru, Rio Solimões, 03°13′S, 060°45′W. MZUSP 6829, 1, 37 mm; Igarapé Tarumã Mirim, Rio Negro drainage, 03°10′S, 060°00′W. MZUSP 7294, 107, 40–70 mm; Igarapé do Rio Maraú, near Maués, municipality of Maués, Rio Maués Açú drainage, 03°24′S, 057°42′W. MZUSP 7351, 67, 40–75 mm; Igarapé Limãozinho, near Maués, municipality of Maués, Rio Maués Açú drainage, 03°24′S, 057°42′W. MZUSP 7415, 3, 60–78 mm; Igarapé do Lago Saracá, municipality of Silves, Rio Amazonas, 02°52′S, 058°22′W. MZUSP 7482, 15, 40–55 mm; stream tributary of Rio Sanbabani, near Silves, municipality of Silves, Rio Amazonas, 02°45′S, 058°20′W. MZUSP 23237, 12, 50–63 mm; Lago Miuá, upstream of Codajás, municipality of Codajás, Rio Solimões, 03°51′S, 060°04′W. MZUSP 28054, 2, 27–64 mm, Pedra do Gavião, Rio Negro, municipality of Moura, Rio Negro drainage, 01°28′S, 061°38′W. MZUSP 30170, 3, 43–44 mm; confluence of Rio Urubaxi with Rio Negro, Rio Negro drainage, 00°31′S, 064°50′W. MZUSP 30065 (part), 2, 23–26 mm; MZUSP 30171, 5, 35–84 mm; Cachoeira do Aracu, Rio Daraá, Rio Negro drainage, 00°28′S, 064°46′W. MZUSP 30172, 384, 40–80 mm; Igarapé Jurupari, municipality of Tefé, Rio Tefé drainage, 03°54′50″S, 065°00′10″W. MZUSP 30173, 11, 40–70 mm; Vista Escura, Rio Tefé, Rio Tefé drainage. MZUSP 30174, 6, 40–60 mm, Lago Mucura, Rio Tefé, Rio Tefé drainage. MZUSP 30175, 7, 40–57 mm, Araná-tuba, Rio Tefé, Rio Tefé drainage. MZUSP 31001, 1, 57 mm; Rio Daraá, Cachoeira do Aracú, 00°25′23″S, 064°46′31″W. MZUSP 47989, 2, 44–59 mm; Igarapé Sirinau, right bank of Rio Cuieiras, 25 km from mouth, near Manaus. MZUSP 62054, 4, 39–44 mm; pool in beach, Tapera, Rio Negro, Rio Negro drainage, 09°11′52″S, 064°04′34″W. MZUSP 74775, 2, 35–60 mm; Igarapé Arraia, right margin of Rio Cuieiras, c. 25 km from mouth, Rio Negro drainage, 02°42′S, 060°20′W.


HYPOPYGUS: PHYLOGENY AND TAXONOMIC REVISION MZUSP 81420, 1, 48 mm, Igarapé Açaí, near Comunidade de São Pedro, Rio Tiquié, Rio Uaupés, Rio Negro drainage, 00°16′N, 069°58′W. MZUSP 86944, 1, 48 mm; Igarapé Sucuriju, Rio Preto da Eva drainage. MZUSP 88821, 1, 65 mm, stream in Rio Preto da Eva drainage, 02°44′35″S, 059°40′08″W. MZUSP 88937, 6, 45–65 mm, stream near Balneário do Encanto da Mata, Rio Preto da Eva drainage, 02°37′10″S, 059°44′30″W. MZUSP 88981, 9, 26–78 mm, Igarapé crossing road-branch of Deus é por Nós, 27 km from Rio Preto da Eva in direction of Manaus, Rio Preto da Eva drainage. MZUSP 88984, 1, 78 mm, Igarapé on the highway to Pousada do Paraíso, Rio Preto da Eva drainage, 02°45′34″S, 059°39′50″W. USNM 304815, 1, 53 mm; Irere, Rio Negro, Rio Negro drainage (locality not determined). Mato Grosso. INPA 6397, 32, 28.2– 50.8 mm; Igarapé in region of Castanhal, municipality of Aripuanã, Rio Aripuanã, Rio Madeira drainage. INPA 29104, 1, 49.7 mm; Rio Juruena, Salto Augusto. INPA 29129, 2, 38.6–45.5 mm; Castanheira, Rio Juruena, Rio Tapajós drainage, Fontalinas. MNRJ 24802, 1, 55 mm; Córrego Água Fria, tributary of Rio Ribeirão Capivara, tributary of Rio Preto, tributary of Rio Auaiá-miçú, Rio Xingú drainage, 10°50′39″S, 052°42′06″W. MZUSP 57478, 1, 68 mm; Rio Areões municipality of Xavantina, Rio Tocantins drainage (Xavantina = 14°41′27″S, 052°21′05″W. MZUSP 88497 (part) 2, 55–61 mm, tributary of Rio Suiazinho crossing BR-158 highway, c. 35 km before Alô Brazil, municipality of Bom Jesus do Araguaia, Rio Suiá-Miçu, Rio Xingú drainage, 12°27′25″S, 051°45′35″W. MZUSP 88498, 2, 58–74 mm; Rio Suiazinho, city of Ribeirão Cascalheira on highway BR-158, Rio Xingú drainage, 12°57′10″S, 051°51′08″W. MZUSP 88499, 2, 56–64 mm, Córrego Capim, tributary of Rio 7 de setembro, c. 16 km north of Canarana, on highway MT-020, 13°30′46″S, 052°23′36″W. MZUSP 88502, 1, 53 mm, Rio Cristalino, 47 km from Cocalinho on highway MT-326, Rio Araguaia drainage, 14°12′45″S, 051°18′21″W. MZUSP 88504, 1, 56 mm, tributary of Rio Suiazinho crossing highway BR-158, 35 km from Alô, municipality of Bom Jesus do Araguaia, Rio Araguaia drainage, 12°27′25″S, 051°43′35″W. MZUSP 88594, 8, 59–65 mm, Mato Grosso, tributary of Rio Corixo da Saudade, c. 17 km north of Cocalinho, on highway MT-426, Rio Araguaia drainage, 14°19′25″S, 051°06′25″W. MZUSP 88598, 1, 48 mm; Rio Ribeirão Agua Preta, tributary of Rio Cristalino, c. 79 km north of Cocalinho on highway MT-326, Rio Araguaia drainage, 14°08′57″S, 051°32′21″W. MZUSP 88599, 10, 48–66 mm, Rio Corixo da Saudade, tributary of Rio Cristalino, c. 42 km north of Cocalinho on highway MT-326, Rio Araguaia drainage, 14°11′14″S, 051°14′58″W. MZUSP 90199, 1, 60 mm, Rio Sepotuba (lower course), municipality of Cáceres Paraguay, Rio Paraguai drainage, 15°47′33″S, 057°39′20″W.

1133

MZUSP 95938, 1, 81 mm, Rio Teles Píres, municipality Itaúba, Rio Tapajós drainage, 10°58′30″S, 055°44′03″W. MZUSP 96252 (part), 3, 94–106 mm; lakes left from gold mining operations, municipality of Paranaíta, Rio Teles Píres, Rio Tapajós drainage, 09°25′44″S, 056°32′36″W. MZUSP 96320, 134, 48–86 mm, Rio Mutum, between towns of Mimoso and Joselândia (Pantanal de Paiaguás), municipality of Barão de Melgaço Paraguay, Rio Paraguai drainage, 16°19′30″S, 055°49′59″W. MZUSP 98006, 1, 61 mm, stream tributary of lake on the Rio Couto de Magalhães, Fazenda Meu Ranchinho, municipality of Campinápolis Xingú, Rio Xingú drainage, 13°47′44″S, 053°03′43″W. MZUSP 100090, 15, 41–56 mm, Rio Teles Píres, upstream of Sete Quedas, municipality of Paranaíta Tapajós, Rio Tapajós drainage, 09°24′05″S, 056°33′49″W. MZUSP 100153, 3, 49–53 mm; Rio Jurena, downstream of PCH Telegráfica, municipality of Sapezal, Rio Juruena, Rio Tapajós drainage, 12°41′09″S, 058°56′31″W. USNM 220447, 2, 55–63 mm; USNM 220449, 37, 40–60 mm; USNM 330445, 4, 53–62 mm; USNM 330449, 37, 45–66 mm; Rio Batovi, Rio Xingú drainage, 11°56′S, 053°36′W. Mato Grosso do Sul. MZUSP 74615, 2, 37–39 mm; near Canarana, Rio Ribeirão do Suaizinho, tributary of the Rio Cascavel, Rio Xingú drainage, c. 13°16′27″S, 052°15′02″W. MZUSP 83572, 2, 35–55 mm, Coxim Paraguai, Ribeirão dos Veados, Rio Taquari, Rio Paraguai drainage, 18°25′21″S, 054°50′06″W. USNM 330447, 2, 57–63, Rio Batovi, Rio Xingu drainage, c. 11°56′S, 053°36′W. Pará. BMNH 1926.10.27.230–239. 10, 76–82 mm; River Amazon at Monte Alegre, c. 02°00′S, 054°04′W. CAS-SU 54497, 1, 77 mm; Urnara Brook into Tapajós, Santarém, Rio Tapajós drainage. INPA 7218, 1, 58.3 mm; INPA 7268, 4, 37–60 mm; Muçum near of mouth of Rio Cupari, municipality of Aveiro, Rio Tapajós drainage. INPA 9832, 1, 46.8 mm; Rio Tapajós, Pimental (locality not determined). INPA 26132, 5, 41.5–48.3 mm; Apuí, pool of Bararati, near Rio Bararati, Rio Tapajós drainage. INPA 26161, 12, 33.8–60.5 mm; Apuí, Rio Bararati, Igarapé do Candirú, Rio Tapajós drainage, 08°21′17″S, 058°36′54″W. INPA 26702, 1, 32.1 mm; Apuí, small pool at Bararati, Rio Bararati, Rio Tapajós drainage. INPA 26710, 10, 31.9–57.3 mm; Apuí, Rio Bararati, Igarapé da Campina, Rio Tapajós drainage. MCP 23354, 10, 50–80 mm; stream on Ihnangapi highway, near São Domingos do Capim, municipality of Ihnangapi, Rio Guamá drainage, 01°27′02″S, 047°48′26″W. MCP 23356, 3, 58–89 mm; Igarapé Ucucure, on highway from Tomé Açu to Moju, c. 49 km east of Tomé Açu, Rio Acará drainage, 02°29′13″S, 048°31′31″W. MCP 23357, 2, 71–82 mm; stream on ParagominasTomé Açu highway, municipality of Tomé Açu, Rio Acará drainage, 02°48′01″S, 048°20′35″W. MCZ 9410,


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1, 73 mm; Rio Amazonas at Óbidos, 01°52′S, 055°30′W. MPEG 1093, 7, 49–92 mm; MPEG 1100, 4, 55–83 mm; MPEG 2423, 27, 50–75 mm; MPEG 2436, 27, 50–85 mm; MPEG 2522, 22, 45–92 mm; MPEG 2605, 7, 47–58 mm; MPEG 2714, 16, 48–70 mm; MPEG 2815, 9, 44–76 mm; Taperebá, Fazenda Santa Maria, Ilha de Marajó, municipality of Cachoeira do Arari, Rio Goiapi drainage, c. 01°00′S,48°57′W. MPEG 1094, 2, 48–67 mm; Rio Tauá, 12–14 km SW of Nova Barcarena, municipality of Barcarena, Rio Barcarena drainage, approx. 01°35′S, 048°41′W. MPEG 1098, 8, 66–97 mm; Rio Guamá near Belém, municipality of Belém, Rio Guamá drainage, approx. 01°28′S, 048°26′W. MPEG 2406, 2, 60–63 mm; Pantanal do Rio Livramento, near steel bridge, municipality of Igarapé Açú, Rio Livramento drainage, approx. 01°07′S, 047°37′W. MPEG 3729, 2, 88–92 mm; MPEG 3731, 2, 41–48 mm; MPEG 6210, 1, 58 mm; MPEG 9945, 1, 94 mm; MPEG 9965, 1, 92 mm; MPEG 9967, 1, 42 mm; MPEG 10008, 2, 57–92 mm; MPEG 10018, 7, 61–90 mm; MPEG 10144, 1, 35 mm; MPEG 10152, 2, 43–53 mm; MPEG 10168, 31, 35–86 mm; MPEG 10169, 9, 57–103 mm; MPEG 10171, 13, 78–99 mm; MPEG 10175, 14, 44–85 mm; MPEG 10176, 1, 96 mm; MPEG 10178, 2, 58–94 mm; MPEG 10430, 2, 47–60 mm; MPEG 10509, 3, 58–87 mm; MPEG 10511, 4, 58–76 mm; Floresta Nacional de Caxiuanã, Estação Científica Ferreira Pena, Rio Curuazinho, municipality of Melgaço, c. 01°44′S, 051°27′W. MPEG 3734, 1, 87 mm; MPEG 3735, 2, 51–53 mm; Floresta Nacional de Caxiuanã, Estação Científica Ferreira Pena, Rio Curuazinho, municipality of Melgaço, Rio Puraquequara, Rio Anapu drainage, c. 01°44′S, 051°27′W. MPEG 4519, 2, 37–62 mm; MPEG 6773, 2, 50–60 mm; Igarapé Poraquequara, municipality of Ourém, Rio Guamá drainage, 01°33′S, 047°06′W. MPEG 4970, 25, 40–84 mm; MPEG 4971, 50, 40–80 mm; Rio Grande, km 18, Pará-Maranhão highway, Rio Guamá drainage, c. 01°42′S, 46°57′W. MPEG 6904, 1, 60 mm; Rio Poraquequara and affluents, municipality of Paragominas, c. 03°00′S, 047°21′W. MPEG 7163, 1, 55 mm; MPEG 7165, 1, 38 mm; Igarapé Tauá, near highway PA 483, municipality of Barcarena, Rio Barcarena drainage, approx. 01°34′0′S, 048°42′0″W. MPEG 7350, 2, 83–87 mm; stream tributary of Igarapé Poraquequara, Fazenda Monte Santo, municipality of Paragominas, Rio Guamá drainage, 03°15′18″S, 047°45′13″W. MPEG 7358, 10,75–93 mm; Igarapé Poraquequara, Fazenda Monte Santo, municipality of Paragominas, Rio Guamá drainage, 03°16′05″S, 047°46′05″W. MPEG 7370, 1, 76 mm; MPEG 7521, 6, 48–92 mm; confluence of Igarapé Cachoerinha and Igarapé Poraquequara, Fazenda Rio Doce, municipality of Paragominas, Rio Guamá drainage, 03°39′25″S, 047°41′51″W. MPEG 7600, 3, 44–47; Rio Quiã-Paranã, near Fazendinha, municipality of Ponte de Pedras,

Ilha de Marajó, 01°21′17″S, 48°55′54″W. MPEG 7999, 4, 34–74, Igarapé Bom Jardim, near Bom Jardim, municipality of Muaná, Rio Atuá drainage, Ilha de Marajó, 01°16′20″S, 049°23′39″W. MPEG 8016, 17, 45–75 mm; Igarapé Jacarequa, municipality of Muaná, Rio Atuá drainage, Ilha de Marajó, 01°16′27″S, 049°19′13″W. MPEG 8042, 1, 50 mm; Igarapé da Divisa, municipality of Mauaná, Ilha de Marajó, 01°17′01″S, 049°16′43″W. MPEG 8839, 3, 56–61 mm; Rio Alto Anapú, municipality of Portel, 02°11′08″S, 051°26′26″W. MPEG 9081, 1, 63 mm; Igarapé Ituá, municipality of Chaves, Ilha de Marajó, 00°10′40″S, 049°56′09″W. MPEG 9538, 1, 47 mm; Igarapé Caratateua, municipality of Aurora do Pará, Rio Alto Anapú, 02°11′08″S, 051°26′26″W. MPEG 9539, 1, 88 mm; Igarapé Candiru, municipality of Paragominas, Rio Guamá drainage, 02°51′51″S, 047°30′50″W. MPEG 9540, 2, 38–58 mm; Igarapé Aneura-Grande, municipality of Tomé-Açú, Rio Guamá drainage, 02°30′03″S, 048°16′53″W. MPEG 9541, 2, 87–97 mm; Igarapé Arrainha, municipality of Tomé-Açú, Rio Guamá drainage, 02°25′11″S, 048°12′13″W. MPEG 10078, 5, 48–76 mm; MPEG 11089, 1, 37 mm; MPEG 11097, 1, 45 mm; Igarapé Socó, Rio Arapiuns, municipality of Juruti, Rio Tapajós drainage, 02°28′14″S, 056°00′13″W. MPEG 10227, 1, 50 mm; MPEG 10246, 5, 57–95 mm; MPEG 10260, 1, 64 mm; MPEG 10264, 1, 55 mm; MPEG 11988, 1, 57 mm; MPEG 11996, 2, 49–60 mm: 12122, 1, 58 mm; MPEG 12168, 4, 32–44 mm; MPEG 12483, 1, 55 mm; MPEG 12484, 1, 69 mm; MPEG 12486, 5, 39–60 mm; MPEG 12516, 11, 45–77 mm; MPEG 11090, 1, 54 mm; Igarapé Taiassuí, municipality of Benevides, 01°24′58″S, 048°13′45″W. MPEG 12156, 1, 50 mm; Igarapé Itá, municipality of Benevides. MPEG 12786, 1, 66 mm; MPEG 12790, 4, 33–45 mm; MPEG 12793, 3, 45–57 mm; MPEG 14166, 2, 63–68 mm; MPEG 14483, 4, 50–78 mm; Igarapé São Francisco, Rio Arapiuns, municipality of Juruti, Rio Tapajós drainage, 02°34′14″S, 055°54′14″W. MPEG 11101, 1, 63 mm; MPEG 11102, 1, 27 mm; MPEG 11106, 2, 57–60 mm; Igarapé Vitória, near Juruti, municipality of Juruti, small stream drainage of Rio Amazonas, 02°10′47″S, 056°04′39″W. MPEG 11108, 1, 27 mm; MPEG 12781, 1, 31 mm; Igarapé Mutum, Rio Arapiuns, municipality of Juruti, Rio Tapajós drainage, 02°36′44″S, 056°11′36″W. MPEG 12782, 2, 77–83 mm; MPEG 12787, 14, 38–53, MPEG 12789, 2, 50–51 mm; MPEG 13643, 2, 62–74 mm; MPEG 13725, 2, 55–72 mm; MPEG 14745, 4, 50–78 mm; Igarapé da Ponte, near Juruti, municipality of Juruti, small stream drainage of Rio Amazonas, 02°10′05″S, 056°04′40″W. MPEG 12783, 1, 47 mm; MPEG 12784, 2, 45–53 mm; MPEG 12785, 2, 55–69 mm: MPEG 12791, 3, 27–63 mm; MPEG 14212, 2, 43–47 mm; Igarapé Itapiranga, municipality of Juruti, Rio Juruti drain-


HYPOPYGUS: PHYLOGENY AND TAXONOMIC REVISION age, 02°28′12″S, 056°06′54″W. MPEG 12792, 2, 37–78 mm; MPEG 12794, 3, 47–50 mm; MPEG 13622, 2, 47–65 mm; MPEG 13723, 14, 49–89 mm; MPEG 14460, 2, 59–67 mm; MPEG 14637, 3, 32–47 mm; confluence of Igarapés Socó and Barroso, Rio Arapiuns, municipality of Juruti, Rio Tapajós drainage 02°27′05″S, 056°00′25″W. MPEG 13615 mm; 1, 56 mm; MPEG 13726, 4, 54–73 mm; MPEG 13728, 3, 58–70 mm; MPEG 14345, 19, 40–70 mm; MPEG 14351, 27, 33–67 mm; MPEG 14366, 1, 67 mm; Rio Arapiuns, municipality of Juruti, Rio Tapajós drainage, Igarapé Mutum, 02°36′46″S, 056°11′37″W. MPEG 14250, 1, 51 mm; Igarapé Guaraná, municipality of Juruti, Rio Juruti drainage, 02°29′46″S, 056°13′50″W. MPEG 15119, 1, 67 mm; MPEG 15332, 1, 43 mm; MPEG 15392, 1, 43 mm; unnamed stream, municipality of Faro, Rio Nhamundá drainage, 01°42′23″S, 057°12′10.1″W. MPEG 17814, 21, 40–62 mm; Igarapé Taiassuí, municipality of Benevides, Rio Guamá drainage, 01°23′46″S, 048°14′59″W. MPEG 18598, 8 (8 recorded, WC08.130210, WC22.130210, WC26.130210 – 31.130210), unnamed stream, 3.6 km and 129° from centre of Bragança, municipality of Bragança, Rio Caeté drainage, 01°41′43″S, 046°44′21″W. MPEG uncatalogued, 2, 50–60 mm (two recorded, WC19.070810, 24.070810), Igarape Açaiteuazinho near Vila de Tauarí, municipality of Capanema, 01°11′45″S, 047°10′51″W, Rio Caeté drainage. MZUSP 7940, 3, 65–73 mm; unnamed stream, tributary of Rio Jamarí, near Terra Santa, 02°07′S, 056°29′W. MZUSP 8211, 3, 65–69 mm, Lago Jacupá, municipality of Oriximiná, Rio Trombetas drainage, 01°46′S, 055°54′W. MZUSP 8413, 49, 49–86 mm, Igarapé Jacundá, Alter do Chão, Rio Tapajós drainage, 02°30′00″S, 054°57′00″W. MZUSP 8490, 16, 50–57 mm; Igarapé Mapiri, Santarém, Rio Amazonas, 02°26′S, 054°44′W. MZUSP 15564, 1, 59 mm; MZUSP 15565, 1, 60 mm; Cabeçeira da Serrinha, Lago Jacaré, Reserva Biológica de Trombetas, Rio Trombetas drainage, 01°20′S, 056°51′W. MZUSP 22274, 1, 54 mm; MZUSP 22277, 2, 27–45 mm; Igarapé Pacuí, km 97, Belém-Brasília highway. MZUSP 23867, 116, 50–83 mm; Caranandéua, Rio Capim, Rio Guamá drainage, 01°23′S, 048°08′W. MZUSP 22893, 11, 74–84 mm; Igarapé Caraparu, Rio Capim, Rio Guamá drainage, 01°23′S, 048°08′W. MZUSP 23889, 1, 44 mm; MZUSP 71847, 2, 30–57 mm; Igarapé Candiru-Mirim, near Badajós Rio Capim, Rio Guamá drainage. MZUSP 23896, 2, 57–78 mm, Lago Jurunundéua, Rio Capim, Rio Guamá drainage. MZUSP 23917, 28, 30–65 mm; Igarapé Ribeira, near Badajós, Rio Capim, Rio Guamá drainage. MZUSP 23941, 2, 72–89 mm; Igarapé Canteiro, near Vila Santana, Rio Capim, Rio Guamá drainage, 02°02′S, 047°45′W. MZUSP 24028, 18, 46–52 mm; Igarapé Mapará, Paraná Sumauma, Rio Tocantins, Rio Tocantins drainage (locality not determined). MZUSP

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24055, 6, 43–73 mm, Igarapé Oxipucu, municipality of Mocajuba, Rio Tocantins drainage, 02°34′S, 49°30′W. MZUSP 24249, 142, 30–70 mm; Igarapé Açu near Aveiro, municipality of Aveiro, Rio Tapajós drainage, 03°35′S, 055°20′W. MZUSP 25380, 4, 55–62 mm, stream at km 55 on highway BR-230, Rio Tapajós drainage, 04°30′00″S, 056°17′00″W. MZUSP 24664, 1, 55 mm (head missing); Aquarium specimen from near Belém, no locality. NRM 15050, 1, 75 mm; right bank of stream draining into Rio Tapajós at city of Santarém, Rio Tapajós drainage, 02°26′S, 054°43′W. UF 36601, 3, 46–74 mm; Estrada Pirelli, near Belém, Rio Guamá drainage, 01°23′51″S, 048°18′29″W. Rondônia. FMNH 97458, 8 (of 10), 42–71 mm; Maciel, Rio Guaporé, c. 12°10′S, 02°50′W. INPA 9714, 1, 72.8 mm; Costa Marques, Rio Guaporé, in front of Costa Marques, Rio Madeira drainage, 012°26′42″S, 064°13′38″W. INPA 9720, 13, 57–81.2 mm; Rio Pacaás Novas, approximately 15 km above Guajará-Mirim, Rio Madeira drainage. INPA 9725, 1, 60.4 mm; Ji-Paraná, Rio Machado, Rio Madeira drainage, 010°53′07″S, 061°57′06″W. INPA 9729 (part), 34, 55.4–69.8 mm; Guajará-Mirim, Rio Guaporé, Rio Pacaás Novas, Rio Madeira drainage. INPA 21837, 3, 56.7–67.2 mm; middle Rio Cautário, Vale do Guaporé, Rio Madeira drainage. MPEG 1097, 4, 37–48 mm; Rio Pacaãs Novas, near Guajará-Mirim, Rio Madeira drainage. UFRO-I 6504, 1, 72 mm; Rio Cautério, near confluence with Rio Guaporé; Rio Madeira drainage, 012°10′50.7″S, 064°34′0.4″W. UFRO-I 7921, 32, 44–99 mm (24 recorded WC01.200610–18.200610; 20.200610–25.200610), Igarapé Mato Grosso, small stream draining into Rio Madeira, 7.7 km and 207° from Porto Velho, municipality of Porto Velho, 08°49′41″S, 064°56′30″W. USNM 330446, 37, 48–80 mm; Rio Guaporé, near Bolivian border, confluence of Rio Pacaãs Novas and the Ouro Preto, between Guajará-Mirim and Mato Grosso, Rio Madeira drainage. Roraima. INPA 1646, 1, 62 mm; Boa Vista, Rio Uraricoera, Rio Branco, Rio Negro drainage. INPA 4393, 9, 34.2–45.1 mm; Boa Vista, Rio Uraricoera, Ilha Maracá, Rio Branco, Rio Negro drainage. INPA 6401, 20, 25.5–39.3 mm; Boa Vista, Rio Uraricoera, Igarapé da Ponta, Ilha Maracá, Rio Branco, Rio Negro drainage. INPA 7398, 65 (out of 68), 35–72.5 mm; INPA 7427, 76, 53.1–81 mm; Boa Vista, Rio Branco, Igarapé Represado, Fazenda Santa Cecília, Rio Branco, Rio Negro drainage. INPA 7399, 3, 52.2–57.4 mm; Boa Vista, Igarapé da Fazenda do Sr. Pedro José, approximately 2.9 km from EMBRAPA in road to Mucajaí, Rio Branco, Rio Negro drainage. INPA 7418, 3, 39.1–71.1 mm; INPA 7422, 2, 59.9–66 mm; Boa Vista, Igarapé Juruaquim, km 26 on road Caracaranã-Surumu, Rio Branco, Rio Negro drainage. INPA 7421, 2, 47.9–49.7 mm; Boa Vista, Rio Uraricoera, Ilha de Maracá, Igarapé da Fazenda do


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José, Rio Branco, Rio Negro drainage. INPA 9830, 3, 26.8–46.5 mm; Boa Vista, Rio Uraricoera, ilha de Maracá, Igarapé da Ponte, Rio Branco, Rio Negro drainage. INPA 16605, 1 (no size data); Rio Jauaperi, BR 174 km 157 of Cachoeira Travessão, Rio Branco, Rio Negro drainage, 0°30′52″N, 060°28′00″W. INPA 30758, 27, 50.9–81.7 mm; Boa Vista, Rio Branco, Rio Negro drainage, 03.3507200°N, 065.7652000°W. MZUSP 23218, 17, 50–69 mm; stream c. 1 km north of Caracaraí, Rio Branco, Rio Branco, Rio Negro drainage, 01°49′N, 061°08′W. MZUSP 23581, 1, 69 mm; MZUSP 23602, 3, 44–65 mm; stream at Fazenda Canadá, Rio Uraricoera, Rio Branco, Rio Negro drainage, 03°28′N, 060°58′W. MZUSP 30177, 5, 38–62 mm; Igarapé do Cujobim, Ilha Maracá, Rio Uraricoera, Rio Branco, Rio Negro drainage, 03°20′N, 061°40′W. MZUSP 30178, 4, 50–53 mm; Igarapé do Bota Panela, Cachoeira do Bem Querer, Rio Branco, Rio Branco, Rio Negro drainage, 01°56′N, 061°00′W. Tocantins. MZUSP 43393, 2 (of 4), 46–53 mm; Lagoa da Buritirama, Parque Nacional do Araguaia, Ilha do Bananal, Rio Araguaia drainage, 10°31′S, 050°15′W. Colombia. Amazonas. IAVHP 3204, 3, 60–86 mm; Río IgaráParaná, near La Chorrera, Río Yapurá (Rio Japurá) drainage, approx. 00°44′S, 73°01′W. Caquetá. CAS-SU 50634, 4, 44–58 mm; small forest stream, tributary of Río Orteguaza, on Tres Esquinas to Solano highway, Río Caquetá, Río Caquetá – Rio Japurá drainage, 0°45′N, 075°15′W. Cundinamarca. UF 111996, 2, 37–48 mm; Río Negro halfway between Caqueza and Puenta, Río Meta, Río Orinoco drainage (Caqueza = 04°24′19″N, 073°56′52″W). Guainía. IAVHP 1340, 1, 56 mm; Caño Guaribes, Puerto Inirida, Río Inirida, Río Orinoco drainage, 03°52′N, 067°55′W. Meta. ANSP 128104, 2, 46–66 mm, Caño Emma, Finca El Viento, c. 33.5 km NE Puerto Lopez (Plancha 268), Río Meta drainage, 04°08′N, 072°39′W. MPUJ 49, 1, 30 mm: MPUJ 570, 7, 37–65 mm; streams in municipality of Puerto Lopez, c. 04°05′N, 072°57′W. UF 33468, 2, 47–55 mm; UF 111994, 3, 32–51 mm; Río Yucao, c. 4.7 km west of Puerto Gaitan, Río Meta, Río Orinoco drainage, 04°20′22″N, 072°09′23″W. Vaupés. CAS-SU 53800, 1, 82 mm; small brook, about 5 km below refugio on Río Guayabero, Río Guaviare, Río Orinoco drainage. USNM 320021, 1, 42 mm; Río Vaupes at Mitú, Rio Negro drainage, 01°17′11″N, 070°13′41″W. Vichada. FMNH 94778, 14, 25–63 mm; 0.5 km south of Río Tomo on Hato Las Sardinas, 04.67°N, 068.00°W. Ecuador. Orellana. FMNH 103353, 1, 56 mm; Río Yasuni, Laguna Jatuncocha, Río Napo drainage. 01.00°S, 075.48°W. FMNH 103354, 3, 46–61 mm; Río Yasuni, stream to Rio Jatuncocha, c. 2 km upstream from Laguna Jatuncocha, Río Napo drainage, 00°10′S, 076°17W. Sucumbios. FMNH 96506, 3, 64.4–77.6 mm, CS; FMNH 102274, 63, 35–102 mm; Tributary of Río Cuyabeno, about 10 km

north of Marian and 1 km south of Río Cuyabeno below road, Río Aguarico, Río Napo drainage, c. 00°2′S, 076°20′W. FMNH 102288, 6, 48–73 mm; Headwater stream of Río Aguas Negras system, c. 0.5 km south of Marian Río Cuyabeno, Río Aguarico, Río Napo drainage, c. 00°2′S, 076°20′W. FMNH 103355, 4, 53–79 mm; tributary to Laguna Grande de Cuyabeno, about 1 km NW East Azanza, Río Aguarico drainage, Río Napo drainage, c. 00°2′S, 076°20′W. FMNH 103356, 1, 66 mm; tributary to Río Cuyabeno, north bank about 3 km upstream from Laguna Grande, Río Aguarico drainage, Río Napo drainage, 00°03′S, 076.22′W. FMNH 103357, 2, 50–55 mm; Laguna Aucacocha, at upper end (Río Cuyabeno – Río Aguarico drainage), Río Aguarico drainage, Río Napo drainage, 00°03′S, 076.20′W. FMNH 103358, 6, 48–76 mm; Tributary to Río Cuyabeno at road to Río San Miguel, Río Aguarico drainage, Río Napo drainage. FMNH 103359, 2, 63–74 mm; FMNH 103360, 10, 42–74 mm; headwater tributary of Río Aguas Negras, 1–2 km north of Marian, just downstream from Río Cuyabeno – Río Aguarico road, Río Aguarico drainage, Río Napo drainage. French Guiana. Saint-Laurent du Maroni. MNHN 1999–1037, 1, 85 mm; Fleuve Grand Inini, Fleuve Maroni, Maroni River drainage, c. 03°26′N, 053°59′W. MNHN 1999– 1329, 1 (no size data), Crique Balaté, near Saint Laurent du Maroni, Fleuve Maroni, Maroni River drainage, c. 05°29′N, 054°03′W. NRM 32239, 7, 73–96 mm; small stream crossing N.1 road near Saut Sabbat, Mana River drainage, c. 05°23′19″N, 053°40′21″W. Cayenne. MNHN 1999–1658, 2, 45–67 mm, Crique Patawa, Fleuve Kaw, Kaw River drainage, c. 04°29′N, 052°02′W. MNHN 2000–1336, 1, 47 mm; Sinnamary River drainage. MNHN 2001– 1973, 1, 83 mm; unnamed creek, Maroni Basin, Maroni River drainage. MNHN 2001–1974, 9, 40–60 mm, no locality data. Guyana. CAS-SU 54615, 2, 68–77 mm; CAS-SU 62934, 1, 78 mm; CAS-SU 66950, 2, 85–86 mm; no locality data. UMMZ 187798, 6, 55–85 mm; no locality data (aquarium trade material). FMNH 103595, 1, 59 mm; Chipoo Creek, no further locality data. Barima/Waini (Region 1). ROM 66517, 2, 21–44 mm; Kwabanna. 7 km from Kwabanna on Moruka logging road, Barama River, Barima-Waini River drainage, 07°33′N, 059°06′W. ROM 66518, 1, 58 mm; Kaniaballi just downstream of Santa Cruz, Barima-Waini River tributary, 07°40′N, 059°14′W. ROM 67920, 1, 47 mm; Santa Rosa Mission at landing for church, Moruka River, Moruka River drainage, 07°39′N, 058°56′W. Demerara-Mahaica (Region 4). AUM 27869, 1, 67 mm; Madewini River, 21.5 miles SSW Georgetown, bearing 207°, Linden Highway bridge, 06°30′05″N, 058°12′45″W. FMNH 85382, 1, 81 mm; downstream from Chung compound in Dakara creek and adjoining swamp forest, Demerara (locality


HYPOPYGUS: PHYLOGENY AND TAXONOMIC REVISION not determined). INHS 49064, 3, 74–78 mm; Conservancy Canal, Maduni stop-off, 22.3 miles south of Georgetown, bearing 176°, Maduni River drainage. 06°30′01″N, 058°02′14″W. INHS 49108, 1, 54 mm, Atlantic Ocean Drive, 5.05 miles SSW Linden, bearing 195°, Demerara River drainage, 05°56.00′N, 058°18.22′W. UMMZ 216857, 1, 73 mm; Yarakabra, tributary of Madewini, north of Thimir Intl. Airport (based on location of Guyana international airport = c. 06°30′N, 058°15′W). East BerbiceCorentyne (Region 6). FMNH 50188, 1 (no size data); head of Itabu Creek, New River, Corentyne (Corantijn) River drainage, 03°23′N, 057°36′W. Potaro-Siparuni (Region 8). ANSP 175965, 15, 36–58 mm, Turtle Pond, small isolated lake some 2.0 km downstream from Essequibo campsite, Essequibo River drainage. ANSP 175966, 7, 45–69 mm, creek tributary of Essequibo River upstream from Maipuri campsite, Essequibo River drainage, c. 04°33′N, 058°31′W. ANSP 175967, 3, 36–47 mm; blackwater creek tributary of Burro Burro River some 15 min upstream from Burro Burro campsite, Essequibo River drainage. ANSP 175968, 23, 35–75 mm; ANSP 175969, 1, 33 mm; clear water creek at campsite 3.1 miles from Kurupukari field station on Kurupukari-Surama River road (Tiger Cr.), Essequibo River drainage, c. 04°42′N, 058°39′W. ANSP 175970, 3, 21–32 mm; creek tributary of Burro Burro River c. 10 min upstream from Burro Burro camp, Essequibo River drainage. ANSP 175971, 31, 35–61 mm; small creeks crossing Kurupukari-Surama River road, c. 3.0 miles from Kurupukari field station, Essequibo River drainage, c. 04°42′N, 058°39′W. ANSP 175972, 4, 41–58 mm; blackwater creek 5 min downstream from Burro Burro campsite, Essequibo River drainage. ANSP 175973, 4, 31–58 mm; forest stream at Burro Burro campsite, Essequibo River drainage. ANSP 175974, 3, 39–44 mm; creek crossing KurupukariSurama River road at A-B Transect Line; 7.1 miles from Kurupukari field station, Essequibo River drainage. ANSP 177480, 1, 50 mm; Essequibo, Tumble Down Creek, Siparuni River, Essequibo River drainage (locality not determined). ANSP 177481, 1, 51 mm; Manicole Creek, Siparuni River, Essequibo drainage. ANSP 177482, 22, 39–69 mm; Red Hill Creek between Levi Falls and Blackwater camp (Iwokrama side), Siparuni River, c. 04°50′N, 058°50′W. ANSP 177483, 4, 53–76 mm; Levi Falls Creek, Siparuni River, Essequibo drainage, c. 04°50′N, 058°50′W. ANSP 177484, 2, 50–51 mm: Demerara, Burro Burro River: Deer Creek upriver from Water Dog Falls, Essequibo River Drainage (locality not determined). ANSP 177485 10, 31–78 mm; small blackwater creek opposite Paddle Rock campsite, Essequibo River drainage (locality not determined). ANSP 177486, 1, 62 mm; Pakatnu Falls Creek, Siparuni River, Essequibo River drainage (locality not determined). ANSP 177487, 1, 59 mm;

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blackwater creek 2.0 km downstream from Paddle Rock campsite, Essequibo River drainage (locality not determined). ANSP 177488, 2, 40–42 mm; Yurrie Creek c. 2.0 km upstream from Paddle Rock campsite, Essequibo River Drainage. ANSP 179501, 3 (no size data); small blackwater creek opposite Paddle Rock campsite, Essequibo river drainage. AUM 28095, 3, 41–45 mm; north side of Potaro River, just downstream of Tumatumari cataract Potaro River, Essequibo River drainage, 05°21′48″N, 059°00′04″W. INHS 49489, 3, 41–51 mm; north side of Potaro River just downstream of Tamatumari Cataract, Potaro River drainage, Essequibo River drainage, 05°21′48.4″N, 059°00′04.4″W. ROM 62549, 1, 51 mm; unnamed creek, c. 7 km south-east of Tambikabo inlet, Essequibo River drainage, 04°46′20″N, 058°45′33″W. Upper Demerara Berbice (Region 10). AMNH 30413, 1, 79 mm; AMNH 35372, 2, 62–74 mm; Malali, MariMari River, Demerara River drainage, c. 05°37′N, 058°21′W. AMNH 33995, 2, 21–35 mm, Kora-Kora Creek, Demerara River drainage (?) (locality not determined). AUM 7857, 1, 43 mm; Creek on Gluck Island, 1.24 miles NW Rockstone, bearing 304°, Essequibo River drainage. AUM 27745, 4, 33–37 mm; Himarakus Creek at Rockstone, Essequibo River drainage, 05°59′08″N, 058°33′03″W. AUM 35860, 5, 40–66 mm; Essequibo River at Kurukupari, east bank, Essequibo River drainage, 04°39′41″N, 058°40′31″W. USNM 341847, 1, 53 mm; Barbaraka Creek, drainage of the Waruni River, Dubulay Ranch, Berbice River drainage, 05°44′N, 057°53′W. Upper Tukutu-Upper Essequibo (Region 9). ANSP 179502, 2 (no size data), unnamed stream at crossing on road between Massara & Karanambo, 10.3 km NW of Karanambo Ranch, Rupununi River drainage, Essequibo River drainage, c. 03°46′N, 059°18′W. ANSP 179503, 1 (no size data), unnamed stream at crossing on road between Massara & Karanambo, 10.3 km north-west of Karanambo Ranch, Rupununi River drainage, Essequibo River drainage. ANSP 179506, 2 (no size data), Circle W Creek (tributary of Pirara River, Ireng-Takutu Dr.), 26.6 km southwest of Karanambo Ranch, Rio Maú, Rio Takutu, Rio Branco, Rio Negro drainage, 03°37′N, 059°40′W. AUM 35817, 1, 34 mm; Sauriwau River, 31.2 km NW village Sand Creek, Takutu River, Rio Branco, Rio Negro drainage. AUM 35886, 3, 46–65 mm; stream 10.3 km NW Karanambo, Rupununi River, Essequibo River drainage, 03°48′27″N, 059°23′06″W. AUM 35862, 1, 50 mm; Rupununi River, 3.7 km SSE Massara, Essequibo River drainage, 03°51′40″N, 059°17′04″W. AUM 35864, 2, 62–70 mm; circle West Creek, tributary of the Pirara River, tributary of the Ireng River, 26.6 km SW Karanambo, Takutu River, Rio Branco, Rio Negro drainage, 03°39′14″N, 059°31′43″W. AUM 35865, 2, 40–48 mm, Yuora River, tributary of the Ireng River, 6.7 km NE Karasabai,Takutu River, Rio Branco, Rio


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Negro drainage, 04°03′14″N, 059°29′07″W. AUM 35867, 1, 80 mm; Moco-Moco River at Moco-Moco Hydro Power Station 18.8 km SE Lethem, Takutu River, Rio Branco, Rio Negro drainage, 03°17′48″N, 059°38′48″W. AUM 38189, 4, 48–57 mm; Kuyuwini River, 48.4 km E Kuyuwini Landing, 182 km SE Lethem, Essequibo River Drainage, 02°03′54″N, 058°48′33″W. AUM 38212, 1, 47 mm; AUM 38353, 2, 44–47 mm; Manari River, 10.2 km NE Lethem, Takutu River, Rio Branco, Rio Negro drainage, 03°26′35″N, 059°44′34″W. AUM 38400, 1, 48 mm; creek 96.8 km SSE Lethem on road from Dadanawa to Aishalton, Rupununi River, Essequibo River drainage, 02°37′39″N, 059°20′55″W. AUM 38935, 2, 55–58 mm; backwater and mainstem of Kuyuwini River, 19.5 km W mouth of Kuyuwini River, Essequibo River drainage, 02°14′27″N, 058°30′03″W. BMNH 1971.10.19.3, 1, 92 mm; tributary of Rupununi River at Karakambo, Essequibo River drainage, c. 03.45°N, 059.04°W. BMNH 1971.10.19.4, 1, 35 mm; Essequibo district, Essequibo River drainage (?). BMNH 1972.7.27.532, 1, 31 mm; Rupunini River, Karanambo Creek, Essequibo River drainage, c. 03.45°N, 059.04°W. BMNH 1973.3.29.5–12, 8, 40–103 mm, Essequibo River, Moraballi, Essequibo River drainage. MCZ 48544, 1, 52 mm; creek 10 miles east of Nappi, Rupununi, Essequibo River drainage. MCZ 48545, 1, 40 mm; Moco-Moco creek, near Lethem, Rupununi, Rio Tacutú, Rio Branco, Rio Negro drainage, 03°19′25″N, 059°39′52″W. MCZ 48546, 3, 38–57 mm; Água Branca, Tributary of Manari River, near Lethem, Rupununi, Rio Tacutú, 03°25′57″N, 059°46′01″W. MCZ 48556, 5, 69–93 mm, small pond, 5 miles north of Manari Ranch, Manari River, Rio Tacutú, Rio Branco, Rio Negro drainage, 03°26′N, 059°46′W. MCZ 59329, 1, 65 mm; Rupununi, near village of Yupakari, Essequibo River drainage. USNM 209202, 1, 67 mm; Crusa Creek up past Limblad’s Camp, drainage not marked. Peru. Loreto. ANSP 165037, 1, 36 mm; small stream c. 70 km S Iquitos near Jenaro Herrera, Río Ucayali drainage, 04°54′N, 073°39′W. ANSP 167723, 1, 36 mm; Río Nanay, drying stream c. 0.5 miles below Santa Clara (right bank), 03°45′S, 073°17′W. INHS 37371, 1, 44 mm; Santa Clara, west of Iquitos, Río Nanay drainage. INHS 43362, 1, 54 mm; Pampa Chica, 4.5 km NW Iquitos, Río Nanay drainage, 03°45′08.8″S, 073°17′00.1″W. NRM 27521, 1, 33 mm; Lago Matamata, near Atalaia do Norte (Brazil), Río Yavarí (Rio Javari) drainage, c. 04°22′S, 070°11′W. MUSM 38687, 22, 34–91 mm (23 recorded for EOD), forest stream near Jenaro Herrera, Río Ucayali drainage, 04°53.577′S, 073°39.011′W. MUSM 38688, 3, 42–82 mm (3 recorded for EOD), forest stream near Jenaro Herrera, Río Ucayali drainage, 04°52.399′S, 073°38.816′W. MUSM 38689, 1, 52 mm (1 recorded for EOD), forest stream near Jenaro Herrera, Río Ucayali

drainage, 04°51′51″S, 073°38′45″W. MUSM 38690, 4, 89–105 mm; forest stream near Jenaro Herrera, Río Ucayali drainage, 04°52′42″S, 073°38′51″W. MUSM 38691, 2, 78–80 mm (2 recorded for EOD); forest stream near Jenaro Herrera, Río Ucayali drainage, 04°54′26″S, 073°36′44″W. MUSM 38692, 5, 49–102 mm (5 recorded for EOD), forest stream near Jenaro Herrera, Río Ucayali drainage, 04°54′40″S, 073°39′29″W. MUSM 38693, 2, 68–78 mm (2 recorded for EOD); forest stream near Jenaro Herrera, Río Ucayali drainage, 04°53′54″S, 073°38′23″W. MUSM 38694, 11, 47–104 mm (11 recorded for EOD); forest stream near Jenaro Herrera, Río Ucayali drainage, 04°55′38″S, 073°39′14″W. MUSM 38695, 12, 55–89 mm; forest stream near Jenaro Herrera, Río Ucayali drainage, 04°54′25″S, 073°36′44″W. MUSM 38696, 3, 83–100 (3 recorded for EOD), forest stream near Jenaro Herrera, Río Ucayali drainage, 04°54.427′S, 073°36.735′W. MUSM 38697, 3, 71–84 mm (3 recorded for EODs), forest stream near Jenaro Herrera, Río Ucayali drainage, 04°53′59″S, 073°38′46″W. MUSM 38698, 1, 113 mm (1 recorded for EOD), forest stream near Jenaro Herrera, Río Ucayali drainage, 04°55′41″S, 073°38′46″W. MUSM 38699, 3, 86–99 mm (3 recorded for EOD); forest stream near Jenaro Herrera, Río Ucayali drainage, 04°54′33″S, 073°39′26″W. MUSM 38700, 1, 59 mm (1 recorded for EOD); forest stream near Jenaro Herrera, Río Ucayali drainage, 04°52′33″S, 073°38′13″W. MUSM 38701, 1, 61 mm (1 recorded for EOD), forest stream near Jenaro Herrera, Río Ucayali drainage, 04°53′58″S, 073°38′51″W. MUSM 39775, 30, 50–80 mm, same locality as MUSM 38701. NRM 27759, 6, 23–34 mm; left bank stream tributary of Río Gálvez, near Colonia Angamos, Río Yavarí (Rio Javari) drainage, approx 05°10′S, 072°53′W. NRM 27760, 2, 46–58 mm; Quebrada Sapuena at km 10 on Jenaro Herrera – Colonia Angamos road, Río Ucayali drainage, 04°54′56″S, 073°34′49″W. NRM 27761, 13, 33–69 mm; stream tributary of Quebrada Sapuena at km 9 on Jenaro Herrera – Colonia Angamos road, Río Ucayali drainage, 04°54′39″S, 073°35′24″W. UF 116558, 4, 47–62 mm (4 recorded: WC03.270301, male, 103 mm; WC05.270301, female, 78 mm; WC06.270301, immature, 76 mm; WC07.270301, female, 74 mm), stream at km 23 on Iquitos-Nauta Road, opposite Cocha ′Encanto del Anaconda′, Río Nanay drainage, 03°56′37.5″S, 073°23′53.7″W. UF 148460, 4, 65–91 mm (4 recorded: WC12.090104, immature, 91 mm; WC13.090104, immature, 65 mm; WC14.090104, male, 66 mm; WC15.090104, female, 53 mm), Quebrada Corventillo in Caserio Correntillo, near Iquitos airport, Río Nanay drainage, 04°49′57″S, 073°21′43″W. UF 148461, 1, 85 mm (WC26.090104, immature); stream, 2 km north of Instituto de Investigaciones de la Amazonia Peruana (IIAP) field station (2.7 km east of Jenaro


HYPOPYGUS: PHYLOGENY AND TAXONOMIC REVISION Herrera), Río Ucayali drainage, c. 04°53′S, 073°39′W. UF 148462, 10, 29–89 mm, tributary of Quebrada Parnayari, c. 1 km south of Jenaro Herrera on trail that begins at km 1, on road from Jenaro Herrera to Colonia Angamos, Río Ucayali drainage, 04°54′40″S, 073°39′56″W. UF 148463, 8, 60–104 mm; UF 148464, 12, 75–105 mm; Quebrada Salomé Caño, c. 9 km E Jenaro Herrera on road to Colonia Angamos, Río Ucayali drainage, 04°54′32″S, 073°35′36″W. UF 148465, 3, 96–103 mm; tributary of Quebrada Parnayari, c. 2 km from Jenaro Herrera – Colonia Angamos road, on path to Requena, Río Ucayali drainage, approx. 04°54′S, 073°37′W. UF 148466, 4, 58–90 mm; tributary to left margin of Quebrada Chica, c. 2 km SSE of Jenaro Herrera on trail to community Pumacahua, Río Ucayali drainage, c. 04°55′S, 073°40′W. UF 148467, 18, 66–107 mm; Quebrada Chica, c. 2 km SSW from Jenaro Herrera on trail to community Pumacahua, Río Ucayali drainage, c. 04°55′S, 073°40′W. UF 148468, 37, 64–97 mm; stream c. 2 km north of km 3.9 on Jenaro Herrera – Colonia Angamos road, Río Ucayali drainage, 04°53′01″S, 073°38′10″W. UF 148469, 2, 67–71 mm; Quebrada Fierro Caño, tributary of Quebrada Sapuenillo, c. 4.3 km north of Instituto de Investigaciones de la Amazonia Peruana (IIAP) field station (2.7 km E of Jenaro Herrera), Río Ucayali drainage. UF 148470, 1, 87 mm; small quebrada, trib. Quebrada Fierro Caño, c. 4 km north of Instituto de Investigaciones de la Amazonia Peruana (IIAP) field station (2.7 km east of Jenaro Herrera), Río Ucayali drainage, 04°51′60″S, 073°38′48″W. UF 176880, 5, 42–77 mm; Río Nanay, 50 km 250° from Iquitos, Río Nanay drainage, 03°53′50″S, 073°40′01″W. UMMZ 228993, 1, 59 mm; Buen Sucesso, Quebrado Carana, Río Javari, Rio Javari drainage. Madre de Dios. MUSM 22640, 2, 47–59 mm; MUSM 03533, 3, 53–66 mm; MUSM 03536, 4, 63–83 mm; Quebrada Planchon, Las Piedras, Tambopata, Río Tambobata, Río Madre de Dios, Rio Madeira drainage, 12°30′S, 69°14′W. Suriname. Marowijne UF 176883, 3, 71–92 mm (3 recorded: WC19.090307, male, 90 mm; WC20.090307, female, 71 mm; WC21.090307, female, 92 mm; small stream on Paramaribo-French Guiana highway, Cottica Rivier, Commewijne Rivier drainage, 05°34.870′N, 054°15.595′ W. UF 176884 12 (1CS) (12 recorded: WC22.090307, female, 85 mm; WC23.090307, female, 81 mm; WC24.090307, female, 88 mm; WC25.090307, 91 mm; WC26.090307, male, 93 mm; WC27.090307, male, 86 mm; WC28.090307, male, 99 mm; WC31.090307, male, 97 mm; WC45.090307, immature, 48 mm; WC46.090307, immature, 44 mm; WC48.090307, male, 97 mm; WC49.090307, female, 75 mm; small stream on Paramaribo-French Guiana highway, Cottica Rivier, Commewijne Rivier drainage, 05°35′13″N, 054°17′07″W. Nickerie. AMNH 54759, 1,

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58 mm; Kapoeri creek, c. 7 km in from junction with Corantijn River, Corantijn River drainage, 05°16′51″N, 057°14′37″W. AMNH 54759, 33, 32–49 mm; Matawai creek, 2 km upstream from small pool (locality not determined). AMNH 54975, 2, 50–53 mm; small stream south of Tiger Falls, Corantijn River drainage, c. 03°56′N, 057°56′W. BMNH 1981.6.9.987–990, 4, 50–76 mm; stream, Lucie River drainage. MZUSP 38267, 1, 50 mm; stream entering Corantijn River at approximately 385 km from mouth, slightly north of Tiger Falls, Corantijn River drainage, c. 03°56′N, 057°56′W. USNM 225553, 1, 33 mm; Lana creek c. 4 km upstream from intersection with Corantijn River, Corantijn River drainage, 05°28′N, 057°15′W. USNM 225554, 9, 20–32 mm; creek opposite Guyanese logging camp 2 1/4 h south of Matapi, c. 2 km, Corantijn River drainage, 04°59′N, 057°38′W. USNM 225555, 1, 83 mm; tributary to Dalbana creek, c. 3 km upstream from where Dalbana creek is crossed by Amotopo to Camp Gelogie Road, Corantijn River drainage. USNM 225556, 1, 37 mm; stream c. 0.5 km inland from Camp Mataway, Corantijn River drainage, 04°48′N, 057°43′W. USNM 225641, 3, 36–49 mm; creek at Camp Macclemmen, Corantijn River drainage, Dalibane creek, 05°34′N, 057°11′W. USNM 225642, 1, 37 mm; Lana Creek, c. 4 km upstream from confluence with W Corantijn River, Corantijn River drainage, 05°28′N, 057°15′W. USNM 225643, 4, 44–53 mm; stream entering Corantijn River c. 385 km north of Tiger Falls, Corantijn River drainage, 04°00′N, 057°43′W. USNM 225644, 1, 39 mm; small creek entering Lucie River about 3 km upstream from junction of Lucie and Corantijn Rivers, 03°35′N, 057°41′W. USNM 225645, 54, 34–63; stream entering Lucie River c. 3 km upstream from confluence of Lucie and Corantijn Rivers, Corantijn River drainage, 03°35′N, 057°39′W. USNM 225646, 2, 33–42 mm; creek on east side of Corantijn River, c. 2 km upstream of mouth of Moskita Creek, Corantijn River drainage, 03°27′N, 057°37′W. USNM 225647, 2, 36–53, small creek entering Corantijn River on east side, c. 300 m north of Amotopo boat landing, 03°33′N, 057°40′W. USNM 225648, 6, 49–56, small creek entering Corantijn River on east side, c. 300 m north of Amotopo boat landing, 03°33′N, 057°40′W. Para. UF 176882, 8, 63–99 mm (1CS) (8 recorded: WC03.050307, male, 94 mm; WC04.050307, female, 87 mm; WC05.050307, male, 94 mm; WC06.050307, female, 91 mm; WC07.050307, male, 99 mm; WC08.050307, female, 81 mm, WC09.050307, 92 mm (CS), WC10.050307, male, 63 mm; Kola Kreek, c. 6 km west of village of Zanderij and Johan Adolf Pengel International Airport, Zanderij municipality, Para Rivier, Suriname Rivier drainage, 05°27′09″N, 054°14′42″W. USNM 330448, 4, 53–72 mm; Carolina of Malasie Kreek, 10 km south-east of Vliegveld Zanderij, Strommend


1140


suur Water. Venezuela. Amazonas. ANSP 162615, 1, 45 mm; Cano of Rio Casiquiare across from beach, 1.5 h from confluence of Río Casiquiare and Río Orinoco, Río Casiquiare drainage. ANSP 162616, 1, 46 mm; Laguna Tonina (cut off), c. 1.0 km from bank of Río Orinoco, 1 km above La Esmeralda, Río Orinoco drainage, 03°10′31″N, 065°33′07″W. ANSP 162617, 1, 49 mm; Cano of Rio Casiquiare, c. 22 km downstream from mouth of Río Pamoni (east side), Río Casiquiare drainage. ANSP 162652, 2, 46–54 mm; Río Autana, c. 8.0 km above confluence with Río Sipapo, Río Orinoco drainage, 04°44′N, 067°37′W. ANSP 165679, 9, 44–48 mm, Caño Horeda, at border of Bolivar-Amazonas, c. 68 km north-east of Puerto Ayacucho, Río Orinoco drainage, 06°08′N, 067°22′W. FMNH 92567, 2, 34–40 mm; 32 km from Puerto Ayacucho, towards San Mariapo. INHS 27645, 7, 33–48 mm; Caño Topocho, bridge on Puerto Paez-Puerto Ayacucho highway, Río Orinoco drainage, 05°56′41″N, 067°22′08″W. MCNG 12427, 9, 27–48 mm; Margin of Río Pasimoni, c. 5 km upstream of Piedra Arapacoa, Department of Casiquiare, Río Casiquiare drainage, 01.8333°N, 066.5833°W. MCNG 13267, 15, 47–57 mm; Caño Chimoni, c. 200 m upstream of mouth of Río Siapa/Matapire, Department of Casiquiare, Río Casiquiare drainage. 02°04′60″N, 066°25′00″W. MCNG 13268, 2, 50–55 mm; Río Pasimoni, c. 20 km upstream of its confluence with Río Casiquiare, Department of Río Negro, 01°49′48″N, 066°34′48″W. MCNG 22091, 1, 20 mm; Río Yureba at San José de Yureba, 30 km from confluence with Río Ventuari, Department of Atabapo, 04°07′00″N, 066°16′60″W. MCNG 24290, 1, 51 mm; Río Putaco near raudal Chicrita-Pora, Department of Atabapo, Río Ocamo, Río Orinoco drainage, 02.9333°N, 064.5500°W. MCNG 26099, 3, 37–50 mm; small stream flowing into Río Siapa, Department of Río Negro. MCNG 26648 (part), 6, 35–38 mm; Caño Topocho on Caicara-Puerto Ayacucho highway, Río Orinoco drainage. MCNG 27027, 1, 36 mm; Río Paria Pequeño, at a bridge c. 33 km south of Puerto Ayacucho, via Samariapo, Río Casiquiare drainage, 05°26′58″N, 067°36′32″W. MCNG 28457, 1, 34 mm; Laguna José, c. 4 km upstream of site ′93–4′, Department of Río Negro, Río Casiquiare drainage, 01°45′50″N, 066°50′20″W. MCNG 30384, 1, 27 mm; Caño El Loro, south of Macuruco, Río Orinoco drainage, 03°56′N, 067°00′W. MCNG 35323, 3, 52–65 mm; Río Casiquiare, en Laguna Curamoni, Río Casiquiare drainage, 02°37′05″N, 066°09′43″W. MCNG 35945, 2, 40–45 mm; Laguna El Sombrero, Río Sipapo, Department of Autana, 04°43′25″N, 067°44′04″W. MCNG 37945 (part), 54, 43–62 mm; Caño Iguarapo, c. 100 m from confluence with Río Casiquiare, after Piedra Culimacare, Department of Río Negro, Río Casiquiare drainage, 01°58′60″N, 066°45′00″W. MCNG 38290, 1, 45 mm; Río Emoni, c. 1–2 km of its confluence with Río

Siapa, Department of Río Negro, Río Casiquiare drainage, 02.1167°N, 066.3333°W. MCNG 42137, 2 (part), 31–37 mm; Laguna de Candela, bank of Río Pasimoni, headwaters of Río Yatua, Department of Río Negro, Río Casiquiare drainage, 01°35′18″N, 066°33′52″W. MCNG 42295, 1, 57 mm; Río Pasimoni at Piedra Guamuribiti, Department of Río Negro, Río Casiquiare drainage, 01°41′02″N, 066°32′48″W. MCNG 45640, 2, 53–63 mm; Caño Tigre, Río Ventuari, Río Orinoco drainage, 04°01′27″N, 066°45′12″W. MCNG 46388, 2, 72–78 mm; Comunidad de ′Maraya′, lower Río Ventauri, Río Orinoco drainage, 03.9900°N, 066.9522°W. MCNG 46940, 1, 35 mm; margin of Caño Yagua, Río Orinoco, 03.5533°N, 066.7533°W. MCNG 48042, 1, 50 mm; Río Yatua at Piedra Catipan, Río Casiaquare, 03°59′24″N, 066°57′08″W. UF 148534, 61, 36–58 mm; Caño Viejita, on road from San Fernando de Atabapo to Santa Bárbara, 16.5 km and 142° from San Fernando de Atabapo town centre, Department of San Fernando de Atabapo, Río Orinoco drainage, 05°55′54″N, 067°36′34″W. UF 148535, 4, 43–58 mm; Caño Samaria, affluent of Río Cataniapo, on road from Puerto Ayacucho to Gavilan, 18.4 km and 131° from Puerto Ayacucho town centre, Department of Puerto Ayacucho, Río Orinoco drainage, 05°33′53″N, 067°28′14″W. UF 148536, 3, 34–55, Caño Culebra, aff. Río Cataniapo, on road from Puerto Ayacucho to Gavilan, 21.5 km and 130° from Puerto Ayacucho town centre, Río Orinoco drainage, 05°32′48″N, 067°28′55″W. UMMZ 228990, 8, 28–63 mm; small creek feeding into Laguna Viejita, near San Fernando de Atabapo, Río Orinoco drainage, 03°45′N, 067°40′W. UMMZ 230806, 3, 23–38 mm, Rio Atabapo, in flooded blackwater of Isla Sapo, Río Orinoco drainage (locality not determined). Apure. ANSP 165741, 3, 47–68 mm; Caño Potrerito, 24 km south of Río Cinaruco, on San Fernando de Apure – Puerto Paez highway, tributary of Río Cinaruco, Río Orinoco drainage, 06°25′N, 067°32′W. AUM 22449, 1, 50 mm; Caño La Pica, c. 75 km. N Puerto Paez on highway to San Fernando, Río Orinoco drainage, 06°53′28″N, 067°30′46″W. AUM 22502, 4, 38–47 mm; Rio Claro, 102 road km N Puerto Paez on highway to San Fernando de Apure, Río Orinoco drainage, 07°09′08″N, 067°07′59″W. CU 72149, 2, 36–38 mm; Caño La Pica, c. 12 km south of Santa Juana in Parque Nacional los Santos Luzarno, Río Capanaparo, Río Orinoco drainage, 06°54′00″N, 067°28′59″W. INHS 27742, 2, 43–47 mm; Caño Maporal, Río Apure, Río Orinoco drainage, 07°14′56″N, 069°19′47″W. INHS 56192, 4, 44–49 mm; Río Claro, Puerto Paez-San Fernando highway, 102 km from Puerto Paez, Río Orinoco drainage, 07°09′08″N, 067°38′06″W. MCNG 11033, 4, 48–55 mm; MCNG 25913, 6, 46–70 mm; Caño Maporal at bridge next to Módulo Fernando Corrales, Department of Muñoz, Río Apure, Río Orinoco drainage, 07°28′40″N, 069°31′10″W. MCNG


HYPOPYGUS: PHYLOGENY AND TAXONOMIC REVISION 26729, 1, 45 mm; Caño La Guardia, near new bridge on San Fernando de Apure-Puerto Páez highway, Río Cinaruco, Río Orinoco drainage, 06°43′35″N, 067°30′39″W. MCNG 28717, 6, 53–60 mm; Módulos de Apure, préstamo no. 36, Department of Muñoz, Río Apure, Río Orinoco drainage, 07°26′50″N, 069°25′05″W. MCNG 36235, 1, 89 mm; Caño la Palmeras, UNELLEZ, Río Apure drainage, Río Orinoco drainage. MCNG 40359, 1, 51 mm; Laguna Guayaba, Department of Pedro Camejo, Río Cinaruco, Río Orinoco drainage, 06°35′23″N, 067°14′24″W. MCNG 41788, 2, 42–50 mm; Río Matiyure at crossing on highway between Mantecal and La Trinidad/Rincón Hondo, Río Apure, Rio Orinoco drainage, 07°26′54″N, 069°06′47″W. MCNG 42487, 2, 57–58 mm; Caño Caicara just west of bridge on Mantecal-Bruzual highway, Department of Muñoz, Río Apure, Río Orinoco drainage, 07°33′51″N, 069°15′50″W. MCNG 42943, 2, 35–42 mm; Río Claro, c. 102 km north of Puerto Paez on highway to San Fernando, Río Orinoco drainage, 07°09′08″N, 067°07′59″W. MCNG 48705, 2, 47–53 mm; Caño La Pica, Río Capanaparo, Río Orinoco drainage, 06°54′00″N, 067°28′59″W. MCNG 51425, 1, 55 mm; Caño Potrerito, 24 km south of Río Cinaruco between San Fernando de Apure and Puerto Paez, Río Cinaruco drainage, Río Orinoco drainage. Bolivar. AMNH 58658, 2 (no size data); Morichal Merecure, 3.5 km east of Río Caura, Río Caura, Río Orinoco drainage, 07°25′30″N, 065°10′00″W. ANSP 135697, 1, 72 mm; Caño Barranca, downstream from Jabillal (opposite bank) on Río Caura, Río Orinoco drainage. ANSP 141577, 4, 50–65 mm; ANSP 169659, 1, 59 mm; isolated lagoon, 200 yards north of Jabillal, Río Orinoco drainage, 06°57′N, 064°50′W. ANSP 160219, 1, 45 mm; Caño 15.1 km east of Río Parguaza ferry crossing on Caicara-Puerto Ayacucho highway, Río Orinoco drainage, 06°26′28″N, 067°09′24″W. ANSP 162657, 1, 50 mm, Marichal Los Pavones, affluent of Río Sipao, behind Hacienda Fundo Malama (Señor Biales), Río Orinoco drainage, 07°35′N, 065°25′W. ANSP 172163, 6, 57–65 mm; small cano tributary of Río Mato (left bank), Río Orinoco drainage. CAS-SU 54611, 1, 57 mm; CAS-SU 58667, 1, 34 mm; Caño de Quiribana, near Caicara. AUM 22305, 3, 47–63 mm; INHS 55538, 3, 43–68 mm; Río Chaviripa, Caicara-Puerto Ayacucho highway, Río Orinoco drainage, 07°07′57″N, 066°29′56″W. UF 80455, 2, 52–61 mm; Río Chaviripa, near bridge on Caicara-Puerto Ayacucho highway, Río Orinoco drainage, 07°13′39″N, 066°29′38″W. MCNG 5698, 3, 42–72 mm; Caño Oche at Finca Mereyal, 43 km north of Pijiguaos, Department of Cedeño, Río Orinoco drainage, 06.7503°N, 066.6417°W. Guarico. MCNG 1908, 1, 33 mm; MCNG 3326, 2, 31–43; Río Aguaro at Hato San Jose del Aguaro, Department of Infante, Río Apure, Río Orinoco drainage 07°57′30″N, 066°28′60″W. MCNG

1141

Figure 25. Hypopygus minissimus, holotype, head, and lateral and dorsal views of body. UF 175389 (WC28.150304), male, 54 mm; Venezuela, Caño Viejita, on road from San Fernando de Atabapo to Santa Bárbara, 16.5 km and 142° from San Fernando de Atabapo, Río Orinoco drainage. Scale bars = 5 mm. Tissue removed from right flank.

11164, 4, 42–69 mm; Caño Garrapata at bridge between Río Parguaza and Villacoa, Río Parguaza, Río Orinoco drainage, 06°19′19″N, 067°07′00″W. MCNG 31526 (part), 2, 60–62 mm; Parque Nacional Aguaro-Guariquito, Morichal Charcote, Río San Bartolo, Department of Infante, 08.4044°N, 066.5731°W. MCNG 31899, 10, 26–45 mm; Parque Nacional Aguaro-Guariquito, Río Aguaro as it crosses Hato Aguaro, east of Santa Rita (Garcerito), Department of Infante, 08°03′06″N, 066°25′34″W.

HYPOPYGUS MINISSIMUS SP. (FIG. 25; TABLE 5)

NOV.

Hypopygus sp. nov. ‘min’. – Crampton & Albert, 2006 [Orinoco basin, list of gymnotiform species]. – Crampton, 2007, table 11.1 [Orinoco basin, list of gymnotiform species]. Diagnosis: Hypopygus minissimus is diagnosed from congeners by the following combination of characters: the absence of oblique bands (versus presence in all congeners), the absence of scales at midbody (versus presence in all congeners), the absence of the sixth infraorbital bone (versus presence in all congeners except H. hoedemani and H. lepturus), the total number of anal-fin rays (102–113 versus 136–170 in all congeners except H. hoedemani and H. lepturus), and the dorsal rami of the intermittent branch of the


Range 59.9 11.9 13.2 49.8 27.4 14 12.1 63.2 44.9 17.9 53.8 11 61 32.1 6.4

(N = 5) (N = 5) (N = 5) (N = 5) (N = 5) (N = 5) (N = 5) (N = 5) (N = 5) (N = 5) (N = 5) (N = 5) (N = 5) (N = 5) (N = 5) (N = 5) (N = 5) (N = 5) (N = 5)

Mean

(N = 27) (N = 27) (N = 27) (N = 27) (N = 27) (N = 27) (N = 27)

2.2–3.7 (N = 20)

54.9–85.4 41.9–56 14.2–23.2 49.2–64 7.5–12.5 58.8–66 18.3–28

12.2–14.4 (N = 27) 11.4–14.4 (N = 27)

46.3–59.7 (N = 27)

38.1–62.8 (N = 27)

45–66.6 (N = 27) 10–12 (N = 27) 11.6–17.7 (N = 27)

22.8–33 (N = 20) 6.4–8.2 (N = 27)

47.7–87.1 (N = 27) 42.9–56.7 (N = 27)

Range

H. neblinae

2.9

62.3 46.8 18.8 63.3 10.2 65.5 26.5

12.8 11.9

56.9

45.6

58.9 11.4 15.7

-

-

Mean

4.2

67.1 48.5 23.8 48.4 58.8 60 24.2

13.2 12.8

40.8

44.6

53.5 9.4 13.5

34 8.3

97 63

H

(N = 7) (N = 7) (N = 7) (N = 7) (N = 7) (N = 7) (N = 7) 3–4.4 (N = 7)

64.6–69.9 47.8–57.1 23.3–33 38.2–49 58.2–66 60–63.7 22.7–28.3

13.2–15.3 (N = 7) 12.5–13.8 (N = 7)

36.1–53.9 (N = 7)

43.5–53.3 (N = 7)

53.7–58.9 (N = 7) 7.9–9.4 (N = 7) 12.7–16.3 (N = 7)

26–34 (N = 7) 7–8.3 (N = 7)

75–97 (N = 7) 49–63 (N = 7)

Range

H. nijsseni

4.1

66.8 49.2 27.3 44.9 59.6 62.9 25.2

14.7 13.1

41.4

44.8

55.4 8.1 13.8

-

-

Mean

Number of specimens indicated in parentheses. H, holotype; range includes holotypes, paratypes, or nontype specimens.

Total length 62 40–62 Length to end of anal 45 33–45 fin Caudal filament length 17 7–17 Head length 6.2 4.9–6.2 Per cent of length to end of anal fin Anal fin length 58.3 57.4–65 Anus to anal-fin base 12.4 10.4–12.4 Body depth at 12.4 12.1–19.6 anal-fin origin Body width at 47.9 47.5–51.9 anal-fin origin Caudal filament 21.8 21.2–37.7 length Head length 14.6 13.7–16 Snout to occiput 9.4 9.4–16.6 Per cent of head length Head depth at eye 64.1 59.4–65 Head width at eye 41.3 39.2–50 Interocular width 19 15–21.1 Pectoral fin length 56.4 52.8–56.9 Orbital diameter 9.7 9.4–13 Postorbital length 62.5 56.4–63.3 Snout length 31.9 28.9–33.3 Per cent of caudal filament Caudal filament 5.4 4.7–8.4 depth

H

H. minissimus

3.5

60 48.2 19.8 64.2 12.5 62.1 54.7

13.2 11.5

51.7

42.3

70 9.5 14.6

29.2 8.4

90 62

H

(N = 7) (N = 7) (N = 7) (N = 7) (N = 7) (N = 7) (N = 7) 3.1–3.8 (N = 6)

58.4–79.4 46.6–56.5 18.7–24.4 63.2–70.2 10.9–16.3 60.6–63.3 52.8–57.9

12.6–13.9 (N = 7) 11–12.5 (N = 7)

45.5–55.5 (N = 7)

41.4–48.4 (N = 7)

54.4–70 (N = 7) 6.9–9.5 (N = 7) 14.6–17.4 (N = 7)

29–40 (N = 6) 8–9.1 (N = 7)

71–112 (N = 7) 58–72 (N = 7)

Range

H. ortegai

Table 5. Morphometrics for examined specimens of Hypopygus minissimus, Hypopygus neblinae, Hypopygus nijsseni, and Hypopygus ortegai

3.2

65.9 49.5 21.7 65.6 13.7 61.1 53.2

13.1 11.2

48.1

45.3

60.3 7.2 12.5

–

– -

Mean



HYPOPYGUS: PHYLOGENY AND TAXONOMIC REVISION anterior lateral line nerve visible as two black parallel lines (versus not visible in H. ortegai). Description: Head and body shape, and pigmentation illustrated in Figure 25. Morphometric data for examined specimens are presented in Table 5. Body size exceptionally small, maximum examined TL 64.0 mm (N = 9). Maximum examined length from snout to end of BC 15.8 mm. No sexual dimorphism in body or head shape observed. Snout slightly convex. Upper jaw slightly longer than lower jaw. Pectoral-fin rays 9–11 [11] (N = 5). Postpectoral EO with two columns and four rows of electrocytes. EO dorsal groove extending to approximately two to two and a half orbital diameters before posterior border of eye. Scales absent on mid-dorsal region of body. Scales above lateral line at midbody 3–4 [4] (N = 5). Scales below lateral line 4 [4] (N = 5). Total anal-fin rays 102–113 [105] (N = 5). Caudal filament moderate in length. Precaudal vertebrae 15–16 (12–13 anterior; 2–4 transitional; N = 2). Pigmentation (Fig. 25): Head and body background coloration uniformly light to dark brown. Pectoral-fin ray, anal-fin ray, and inter-radial membranes hyaline, sporadically speckled with dark chromatophores. Conspicuous absence of oblique bars, spots, or other markings. Dorsal rami of intermittent branch of anterior lateral line nerve visible as two black parallel lines on each side of upper back, from approximately one to one-half pectoral fin lengths behind the occiput, running posteriorly to mid-dorsal portion of body. Lateral line nerve visible as dark line, extending from above pectoral fin to approximately two-thirds into caudal filament. Electric organ discharge: Data available only from four specimens at the type locality. Hypopygus minissimus generates a tetraphasic EOD (Fig. 17) ranging in duration from 0.80 to 1.13 ms (mean 1.00, N = 4), and with a peak power frequency ranging from 2.28 to 2.615 kHz (mean 2.612, N = 4). Mean pulse rate during the day range from 54.1 to 67.1 Hz [mean 60.8, CV 3.59, N = 4], and during the night from 64.1 to 72.3 Hz (mean 69.41, CV 2.04, N = 4). Distribution: Hypopygus minissimus is known only from the upper Orinoco in Venezuela (vicinity of San Fernando de Atabapo, Río Cunucunuma, and Río Sipapo), and from a tributary of the Casiquiare canal in Venezuela (Río Candela) (Fig. 26). Ecology: Hypopygus minissimus is known only from small rainforest and savannah creeks. In the vicinity of San Fernando de Atabapo, Amazonas, Venezuela, it

1143

1

Figure 26. Map of northern South America showing collection records of Hypopygus minissimus. Some symbols represent more than one nearby collecting locality.

is uncommon, and occurs sympatrically with three other Hypopygus species: H. isbruckeri (uncommon), H. lepturus (uncommon), and H. neblinae (common). One stomach content was examined from this species. It contained Chironomidae larvae, and small Coleoptera larvae. Etymology: The specific epithet, minissimus, is from the superlative of the Latin minimus (smallest), in reference to the status of this species as the smallest known gymnotiform. Remarks: Hypopygus minissimus possesses four autapomorphies: the loss of the second mandibular canal bone; the loss of the anterior portion of the supraorbital canal; the loss of scales along the mid-dorsal region of body; and the absence of oblique bands on the lateral and dorsal regions of body. It is the smallest member of the genus and the smallest of all known gymnotiforms. Material examined: (Nine specimens.) Holotype. Venezuela, Amazonas. UF 175389, WC28.150304, male, 54 mm; Caño Viejita, moriche palm swamp in savannah, road from San Fernando de Atabapo to Santa Bárbara, 16.5 km and 142° from San Fernando de Atabapo, Río Orinoco drainage, 03°55′59.0″N, 067°36′34.2″W; W. Crampton et al., 15.iii.2004. Paratypes. Venezuela. Amazonas. UF 148533, 5, 40–62 mm (3CS) (3 recorded: WC15.120304, female, 44 mm; WC41.120304, female, 42 mm, CS; WC29.150304, immature, 42 mm, CS); same location as holotype; W. Crampton et al., 12–15.iii.2004. Nontypes. MBUCV-V 25679, 1, 62 mm; stream to east of Río Cunucunuma, c. 62 km from Río Orinoco, Río Orinoco drainage, 03°31′42″N, 065°56′45″W; collector not listed, 23.iii.1987. MCNG 21830, 1 male 64 mm; Río Sipapo near Salto Remo, Department of Altures, Río Orinoco drainage, 04°34′28″N, 067°18′31″W; L. Nico et al., 31.v.1989. MCNG 42201, 1 female, 48 mm; Caño Candela near confluence with


1144

C. D. DE SANTANA and W. G. R. CRAMPTON H. minissimus), the dorsal rami of intermittent branch of anterior lateral line nerve visible as two black parallel lines (versus not visible in H. ortegai), the distance from the anus to the anal-fin ray (10.0– 12.0% of LEA versus 7.9–9.4 in H. nijsseni, and 6.5– 9.5 in H. ortegai), and the number of scales above the lateral line (three to five versus eight to nine in H. isbruckeri).

Figure 27. Hypopygus neblinae, nontype, head, and lateral and dorsal views of body. UF 148540 (WC49.150304), female, 78 mm: Venezuela, Caño Viejita, on road from San Fernando de Atabapo to Santa Bárbara, 16.5 km and 142° from San Fernando de Atabapo town centre, Río Orinoco drainage. Scale bars = 5 mm.

Río Pasimoni, Río Candela, Río Casiquiare drainage, 01°32′06″N, 066°34′34″W; L. Nico, H. Jelks, H. López et al., 10.i.1999.

HYPOPYGUS NEBLINAE MAGO-LECCIA (FIG. 27; TABLE 5) Hypopygus neblinae Mago-Leccia, 1994: 86, fig. 96 [original description; Venezuela, Amazonas, Río Baría, 3 km downstream of La Neblina base camp, holotype MBUCV-V-14694]. – Provenzano, Marcano & Mondaca, 1998, 11 [listing in type catalogue for MBUCV-V]. – Albert & Crampton, 2003: 495 [in listing of species of the genus; Orinoco basin]. – Crampton & Albert, 2006 [Orinoco basin, list of gymnotiform species]. – Crampton, 2007, table 11.1 [Orinoco basin, list of gymnotiform species]. Diagnosis: Hypopygus neblinae is diagnosed from congeners by the following combination of characters: the total number of anal-fin rays (137–145 versus 102– 135 in H. hoedemani, H. lepturus, and H. minissimus; 155–174 in H. cryptogenes), the presence of the sixth infraorbital bone (versus absence in H. hoedemani, H. lepturus, and H. minissimus), the presence of oblique bands (versus absence in H. minissimus), the presence of scales at midbody (versus absence in

Description: Head and body shape, and pigmentation illustrated in Figure 27. Morphometric data for examined specimens are presented in Table 5. Body size moderate, maximum examined TL 119.2 mm (N = 448). Maximum examined length from snout to end of BC 16.2 mm. No sexual dimorphism in body or head shape. Snout blunt. Upper jaw slightly longer than lower jaw. Pectoral-fin rays ten to 11 (N = 9). Postpectoral EO with two columns and five to seven rows of electrocytes. EO dorsal groove extending anteriorly to approximately one orbital diameter behind posterior border of eye. Scales present on mid-dorsal region of body. Scales above lateral line at midbody three to five (N = 9). Scales below lateral line three to five (N = 5). Total anal-fin rays 137–145 (N = 9). Caudal filament moderate. Precaudal vertebrae 15 (12 anterior; three transitional; N = 6). Pigmentation (Fig. 27): Body background light brown, speckled with dark chromatophores. Clear oblique bands from nape to end of caudal filament. Eighteen to 24 clear bands crossing dorsal region of body, counted from nape to last anal-fin ray. Mid-dorsal portion of body with sparse pale bands. Head light to dark brown, sometimes with a depigmented area at ventroposterior portion to eye. Pectoral-fin ray and inter-radial membrane hyaline, sporadically speckled with dark chromatophores. Prominent and regularly spaced series of V-shaped dark patches at base of anal fin pterygiophores along length of anal fin, extending about one half distance to dorsal edge of pterygiophores. Anal-fin ray and inter-radial membrane hyaline, or lightly speckled with dark chromatophores. Dorsal rami of intermittent branch of anterior lateral line nerve visible as two black parallel lines on each side of upper back from approximately one to one-half pectoral fin length behind the occiput, running posteriorly to mid-dorsal portion of body. Lateral line nerve visible as dark line, extending from above pectoral fin to approximately two-thirds into caudal filament. Electric organ discharge: Data available from near area of type locality, in the area of San Fernando de Atabapo, Amazonas, Venezuela. Hypopygus neblinae generates a tetraphasic EOD (Fig. 17) ranging in



1

2 3

Figure 28. Map of northern South America showing collection records of Hypopygus neblinae (circles), Hypopygus nijsseni (squares), and Hypopygus ortegai (triangles). Some symbols represent more than one nearby collecting locality.

duration from 2.109 to 3.443 ms (mean 2.623, N = 24), and with a PPF ranging from 0.715 to 1.359 kHz (mean 1.112, N = 24). Mean pulse rate during the day range from 28.4 to 47.3 Hz (mean 39.5 Hz, CV 4.2, N = 12) and during the night from 38.6 to 57.2 Hz (mean 46.4, CV 8.04, N = 8). Distribution: Hypopygus neblinae is known from the middle and upper Río Orinoco and the upper Río Meta of Venezuela, the Casiquiare canal of Venezuela, and the Rio Negro and Rio Preto da Eva drainages of Brazil (Fig. 28). Ecology: In the region of San Fernando de Atabapo, Amazonas, Venezuela, H. neblinae is common in small rainforest and savannah creeks. It occurs in marginal roots, in submerged leaf litter and branches, and in aquatic vegetation. In this region it occurs in sympatry and syntopy with three less common species: H. isbruckeri, H. lepturus, and H. minissimus. Stomach contents (N = 5 examined) contained autochthonous aquatic invertebrates – mostly Chironomidae larvae, small Coleoptera and Ephemeroptera larvae, and unidentified insect parts. Remarks: The presence of a ventral ethmoid partially fused to the parasphenoid is an autapomorphy for H. neblinae. Material examined: (448 specimens.) Brazil. Amazonas. INPA 29934, 1, 68.9 mm; PDBFF/km 37, near Manaus, Rio Urubu drainage, 02°24′46″S, 059°46′27″W. INPA 30328, 1, 54.3 mm; Igarapé Ajuricaba, near Presidente Figueredo, Rio Urubu drainage, 02°07′04″S, 059°56′06″W. INPA 30725, 1, 59 mm; Rio Preto da Eva, Rio Preto da Eva drainage, 02°44′27″S, 059°40′17″W. MPEG 1099 (part), 5, 30–64 mm; Anavilhanas archipelago of Rio Negro, municipality of Novo Airão, Rio Negro drainage, c. 02°44′S, 060°40′W. MPEG 1101 (part), 8,

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35–67 mm; Igarapé Tarumã Grande, municipality of Manaus, c. 02°55′S, 060°06′W, Rio Negro drainage. MZUSP 95239, 2, 48–69 mm; unnamed lake on margin of Rio Negro, Santa Isabel do Rio Negro, Rio Negro drainage, 00°31′S, 065°01′W. Colombia. Meta. ANSP 128097, 3, 62–89 mm; stream entering Lago Mozambique, Mozambique Ranch, Río Meta drainage, Río Orinoco drainage, 03°58′N, 073°04′W. ANSP 128202, 28, 45–62 mm; Caño Rico at La Defesa, north-west of Laguna Mozambique, becomes Caño Buenaventura before entering Río Negro, Río Meta, Río Orinoco drainage, 03°59′N, 073°08′W. MPUJ 136, 6, 43–88 mm; MPUJ 138, 6, 40–43 mm; MPUJ 139, 2, 22–25 mm; MPUJ 340, 1, 40 mm; MPUJ 343, 1, 51 mm; MPUJ 392, 2, 27–89 mm; MPUJ 427, 12, 51–61 mm; MPUJ 435, 5, 31–104 mm; MPUJ 639, 6, 37–50 mm; MPUJ 726, 1, 42 mm; MPUJ 2497, 1, 75 mm; streams in municipality of Puerto Lopez, c. 04°05′N, 072°57′W. Venezuela. Amazonas. AMNH 58648, 1, paratype, 76 mm; AMNH 58669, 3, paratypes, 63–79 mm; AMNH 58670, 2, paratypes, 60–74 mm; Chamuchina, Río Atabapo, Río Orinoco drainage, 03°46′49″N, 067°37′35″W. ANSP 162126, 1, paratype, 72 mm; small stream c. 5 km below Raudal Peresa, Río Autana, Río Sipapo, Río Orinoco drainage, 04°46′N, 067°19′W. ANSP 162618, 4, 32–63 mm; outflow stream from morichals, c. 5 km from mouth of Río Pamoni, Río Casiquiare drainage. BMNH 2000.4.14.2–3, 2, 59–66 mm; Caño Manu, 250 m upstream of Solano, tributary of Río Casiquiare, Río Casiquiare drainage. FMNH 92567, 1, 82 mm; stream 32 km from Puerto Ayacucho on road towards San Mariapo. INHS 44483, 1, 69 mm; Caño Topocho, bridge on Puerto Paez-Puerto Ayacucho highway, Río Orinoco drainage, 05°56′41″N, 067°22′08″W. MBUCV-V 12997, 23 (no size data); MBUCV-V 12998, paratypes 10 (of 14), 68–74 mm; Rio Atabapo, mouth of stream in front of Ilha Chamuchina. MBUCV-V 14694, 1, holotype, 119.2 mm; Río Baria, c. 3 km downstream of Pico Neblina camp, Río Casiquiare drainage, c. 01°28′N, 066°31′W. MBUCV-V 14741, 79 (no size data); Caño Manu, affluent of Río Casiquiare, c. 250 m upstream of Solano, Río Casiquiare drainage. MCNG 2660, 2, 54–57 mm; MCNG 7857, 1, 57 mm; Caño Yatuje at end of airstrip, Department of Atures, Río Orinoco drainage, 05°36′22″N, 066°07′15″W. MCNG 3017, 5, 36–57 mm; Río Manapiare, near Yutaje, Department of Atures, Río Orinoco drainage, 05°34′60″N, 066°17′50″W. MCNG 6846, 1, 68 mm; stream west of Buena Vista, near Río Meta, Río Meta drainage, Río Orinoco drainage, 06°10′20″N, 068°35′50″W. MCNG 21517, 9, 25–63 mm; Río Guainia at Maroa, Department of Casiquiare, Río Negro drainage, 02°43′60″N, 067°34′00″W. MCNG 28456, 1, 67 mm; Laguna José, c. 4 km upstream of site ′93–4′, Department of Río Negro, Río Yatuá


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drainage, Río Casiquiare drainage, 01°45′50″N, 066°50′18″W. MCNG 35143, 4, 47–79; Laguna Cadamuhedeyedi, Río Casiqiuare, Río Casiqiuare drainage, 02.3736°N, 066.5181°W. MCNG 35322, 1, 68 mm; Laguna Curamoni, Río Casiquiare, 02°22′25″S, 066°31′52″W. MCNG 38072, 1, 69 mm; stream connecting Laguna Cumacapi with Río Siapa, Department of Río Negro, Río Siapa drainage, Río Casiquiare drainage, 01°57′00″N, 066°00′00″W. MCNG 38124, 3, 37–57 mm; Caño Buridajow near its confluence with Río Pasimoni, Department of Río Negro, Río Casiquiare drainage. MCNG 42137, 58 (part), 60–80 mm; Laguna de Candela, bank of Río Pasimoni, headwaters of Río Yatua, Department of Río Negro, Río Casiquiare drainage, 01°31′42″N, 066°33′52″W. MCNG 42200, 2, 72–75 mm; Río Candela near confluence with Río Pasimoni, Department of Río Negro, Río Casiquiare drainage, 01°21′18″N, 066°34′34″W. MCNG 26648 (part), 2, 60–70 mm; Caño Topocho on Caicara-Puerto Ayacucho highway, Río Orinoco drainage. MCNG 37945 (part), 3, 58–66 mm; Caño Iguarapo, c. 100 m from confluence with Río Casiquiare, after Piedra Culimacare, Department of Río Negro, Río Casiquiare drainage, 01°58′57″N, 066°45′00″W. UMMZ 228991, 1, 66 mm; creek near Puerto Ayacucho. UMMZ 228995, 1, 36 mm; UMMZ 230805, 1, 30 mm; ‘El Pozo de Lucas’, 11 km E San Fernando, tributary of Río Orinoco, Río Orinoco drainage, 03°59′23″N, 067°38′15″W. UF 148538, 1 female (WC19.110304), 87 mm; Pozo ‘CVG’ (Corporacion Venezuelana Guyana), on road from San Fernando de Atabapo to Santa Bárbara, 10.5 km and 140° from San Fernando de Atabapo town centre, 03°58′57″N, 067°38′29″W. UF 148540 109, 50–89 mm (5 CS) (23 recorded: WC11.130304, female 65 mm; WC12.130304, female, 81 mm (CS); WC13.130304, female, 49 mm; WC14.130304, female, 74 mm (CS); WC15.130304, immature, 80 mm; WC26.150304, immature, 68 mm (CS); WC27.150304, immature, 58 mm; 36.150304, female, 77 mm; WC37.150304, immature, 89 mm; WC39.150304, female, 73 mm; WC40.150304, immature 59 mm; WC41.150304, female, 81 mm (CS); WC42.150304, female 77 mm; WC43.150304, immature, 73 mm; WC44.150304, male, 82 mm; WC45.150304, immature 78 mm; WC46.150304, immature, 70 mm; WC47.150304, immature, 72 mm; WC48.150304, female, 76 mm (CS); WC49.150304, female, 79 mm; WC50.150304, immature, 75 mm; WC51.150304, immature, 71 mm; WC52.150304, immature, 73 mm); Caño Viejita, on road from San Fernando de Atabapo to Santa Bárbara, 16.5 km and 142° from San Fernando de Atabapo, Río Orinoco drainage. Apure. INHS 27708, 7, 72–78 mm; Río Cinaruco, on San Fernando to Puerto Paez highway, Río Orinoco drainage, 06°33′06″N, 067°30′43″W.

MCNG 26652, 26, 27–70 mm; Caño Señor Miguel, just to west of Galeras de Cinaruco, Department of Pedro Camejo, Río Cinaruco drainage, Río Orinoco drainage, 06°34′24″N, 067°17′57″W. MCNG 26697, 8, 48–76 mm; lake to west of the Cinaruco highway, Department of Pedro Camejo, Río Cinaruco drainage, Río Orinoco drainage 06°33′06″N, 067°30′43″W. MCNG 28198, 7, 39–59 mm; Caño Maporal, Department of Muñoz, Río Apure drainage, Río Orinoco drainage, 07°25′30″N, 069°35′44″W. MCNG 28709, 4, 36–52 mm; Módulos de Apure, Department of Muñoz, Río Apure drainage, Río Orinoco drainage, 07°27′10″N, 069°25′15″W. Bolivar. ANSP 162656, 2, 47–58 mm; Morichal, Merecure, 3.5 km east of Rio Caura and 1.0 km north of Caicara, Ciudad Bolivar highway, Río Orinoco drainage, 07°25′30″N, 065°10′00″W. ANSP 169660, 11, 74–79 mm; Morichal Zamorai (caño) between Río Tauca and Río Tiquire on Maripa-Ciudad Bolivar highway; Río Orinoco drainage, 07°28′N, 064°54′W. CAS-SU 58787, 1, 55 mm; CAS-SU 54491, 1, 63 mm; Caño de Quiribana, near Caicara. Guarico. MCNG 15997, 6, 46–68 mm; Rio Chaviripa at bridge on the Caicara – Puerto Ayacucho highway, Río Orinoco drainage, 07°07′59″N, 066°30′00″W. MCNG 31526 (part), 36, 45–60 mm; Parque Nacional Aguaro-Guariquito, Morichal Charcote, Río San Bartolo, Department of Infante, 08°24′16″N, 066°34′23″W. Country and locality unspecified: USNM 330450, 2, 85–96 mm; ‘South America’.

HYPOPYGUS NIJSSENI SP. NOV. (FIGS 23B, 29; TABLE 5) Diagnosis: Hypopygus nijsseni is diagnosed from congeners by the following combination of characters: the total number of anal-fin rays (145–152 versus 102–135 in H. hoedemani, H. lepturus, and H. minissimus; 155–174 in H. cryptogenes), the presence of the sixth infraorbital bone (versus absence in H. hoedemani, H. lepturus, and H. minissimus), the presence of oblique bands (versus absence in H. minissimus), the presence of scales at midbody (versus absence in H. minissimus), the dorsal rami of intermittent branch of anterior lateral line nerve visible as two black parallel lines (versus not visible in H. ortegai), the head length (13.2–15.3% of LEA versus 12.6–13.9 in H. ortegai), the distance at the nape (12.5–13.8% of LEA versus 11.0–12.5 in H. ortegai), the total number of pectoral fin rays (ten to 12 versus 12–16 in H. isbruckeri), the number of scales above the lateral line (five to six versus seven to eight in H. isbruckeri), and the distance from the anus to the anal fin (7.9–9.4% of LEA versus 10.0– 12.0 in H. neblinae).



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distance to dorsal edge of pterygiophores. Pectoral-fin ray and interradial membrane hyaline. Anal-fin ray hyaline and interradial membrane hyaline. Dorsal rami of intermittent branch of anterior lateral line nerve visible as two black parallel lines, on each side of upper back from approximately one to one-half pectoral fin length behind the occiput, running posteriorly to mid-dorsal portion of body. Lateral line nerve visible as dark line, extending from above pectoral fin to approximately two-thirds into caudal filament.

Figure 29. Hypopygus nijsseni, holotype, head, and lateral and dorsal views of body, 96 mm, MCP 44650, immature; Brazil, Amazonas, Rio Tefé, Lago Tefé, Igarapé Repartimento on road from Tefé to Agrovila, 03°24′28″S, 64°44′10″W. Scale bars = 5 mm.

Description: Head and body shape, and pigmentation illustrated in Figures 23B and 29. Morphometric data for examined specimens are presented in Table 5. Body size moderate, maximum examined TL 95.0 mm (N = 15). Maximum examined length from snout to end of BC 18.7 mm. Sexual dimorphism in body or head shape not possible to document. Snout slightly convex. Upper jaw slightly longer than lower jaw. Pectoral-fin rays ten to 12 [12] (N = 7). Postpectoral EO with two columns and five to six rows of electrocytes. EO groove extending approximately two to two and half orbital diameters behind posterior border of eye. Scales present on mid-dorsal region of body. Scales above lateral line at midbody four to five [five] (N = 7). Scales below lateral line five to six [six] (N = 2). Total anal-fin rays 145–154 [154] (N = 7). Caudal filament moderate. Precaudal vertebrae 15 (11 anterior; four transitional; N = 6). Pigmentation (Fig. 29 and Fig. 23B for colour of live specimen): Body background dark brown. Light tan vertical bands extending from across dorsal surface to margin of anal fin, from nape to end of caudal filament (15-18 crossing dorsal region of body counted from nape to last anal-fin ray). Light bands thinner in mid-body. Head dark brown, sometimes with a depigmented area ventroposterior to eye. Prominent series of more or less regularly spaced inverted U-shaped dark spots over pterygiophores, at margin of anal fin, separated by light margins, extending about one half

Electric organ discharge: Data available only from four specimens at the type locality, in the vicinity of Tefé, Amazonas, Brazil. Hypopygus nijsseni generates a tetraphasic EOD (Fig. 17) ranging in duration from 1.01 to 1.69 ms (mean 1.36, N = 4), and with a PPF ranging from 1.991 to 2.175 kHz (mean 2.069, N = 4). Mean pulse rate during the day ranges from 44.0 to 51.8 Hz (mean 48.3, CV 1.06, N = 4), and during the night from 49.3 to 57.8 Hz (mean 55.4, CV 2.80, N = 4). Distribution: Hypopygus nijsseni is known only from small streams in the vicinity of Tefé (Fig. 28). Ecology: In the Tefé region H. nijsseni was found rarely in small rainforest streams (approximately 1–4 m across and up to 1.5 m deep), where it was found in marginal roots and submerged structures, near conspecifics. A single specimen was found in shallow flooded forest in the floodplain of the Rio Tefé, in the lower reaches of a terra firme stream. Stomach contents (N = 5) contained only autochthonous aquatic invertebrates – mostly Chironomidae larvae, but also the larvae of Ephemeroptera, Coleoptera, and Trichoptera. Hypopygus nijsseni co-occurs syntopically with the much more abundant H. lepturus without any obvious partitioning of microhabitat or diet. Etymology: The specific epithet, nijsseni, is a patronym in honour of Hans Nijssen for his contribution to Neotropical ichthyology. Remarks: Hypopygus nijsseni possesses two osteological autapomorphies: both the fourth and fifth basibranchials are ossified. Material examined: (15 specimens.) Holotype. Brazil, Amazonas, MCP 44650, 1, 91 mm, WC04.240201, female; Igarapé Repartimento, 1.5 km downstream from Estrada Agrovila, c. 7 km and 230° from Tefé, municipality of Tefé, tributary of Lago Tefé, Rio Tefé drainage, 03°24′30″S, 064°44′12″W; W. Crampton, 24.ii.2001.


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C. D. DE SANTANA and W. G. R. CRAMPTON species), the total number of anal-fin rays (137–147 versus 102–135 in H. hoedemani, H. lepturus, and H. minissimus; 155–174 in H. cryptogenes), the presence of the sixth infraorbital bone (versus absence in H. hoedemani, H. lepturus, and H. minissimus), the presence of oblique bands (versus absence in H. minissimus), the presence of scales at midbody (versus absence in H. minissimus), the head length (12.6– 13.9% of LEA versus 13.2–15.3 in H. nijsseni), the distance at the nape (11.0–12.5% of LEA versus 12.5– 13.8 in H. nijsseni), the distance from the anus to the anal-fin ray (6.5–9.5% of LEA versus 10.0–12.0 in H. neblinae), and the head length (12.6–13.9% of LEA versus 13.2–22.9 in H. isbruckeri).

Figure 30. Hypopygus ortegai, holotype, head, and lateral and dorsal views of body, 107 mm, MUSM 35305 (WC02.160104, female); Peru, Loreto, small unnamed stream, 2 km north of km 3.9 on road from Jenaro Herrera to Colonia Angamos, 04°53′01″S, 073°38′10″W, Loreto, Peru. Scale bars = 5 mm.

Paratypes. Brazil, Amazonas, MCP 44737, 4, 73–96 mm, all immature (2 CS); same locality as holotype; W. Crampton, 29.xi.2000. MCP 44738, 3, 82–94 mm, 1 immature (82 mm, CS), 2 male (83– 94 mm); same locality as holotype; W. Crampton, 24.i.2001. MCP 44739, 2, 72–79 mm, 1 male (72 mm), 1 female (79 mm); same locality as holotype; W. Crampton, 02.iii.2001. MCP 44740, 1, 70 mm (WC01.070701, immature); near Ilha do Martelo, Rio Tefé, 57 km and 214° from Tefé, municipality of Tefé, Rio Tefé drainage, c. 03°46′S, 064°59′W, W. Crampton, 7.vii.2001. MCP 44651, 4, 74–92 mm (2CS) (2 recorded: WC01.240201, immature, 76 mm; WC05.240201, male, 74 mm); same collecting data as holotype.

HYPOPYGUS ORTEGAI SP. NOV. (FIGS 23C, 30; TABLE 5) Stegostenopos cryptogenes: – Crampton & Albert, 2006: 672, figure 23.8 [Amazon basin, photograph of head, with EOD waveform]. Diagnosis: Hypopygus ortegai is diagnosed from congeners by the following combination of characters: the dorsal rami of intermittent branch of anterior lateral line nerve not visible (versus visible in remain

Description: Head and body shape, and pigmentation illustrated in Figures 23C and 30. Morphometric data for examined specimens are presented in Table 5. Body size moderate, maximum examined length 126 mm (N = 114). Maximum examined length from snout to end of BC 21.3 mm. No sexual dimorphism in body or head shape. Snout slightly convex. Upper jaw slightly longer than lower jaw. Pectoral-fin rays 11–12 [11] (N = 7). Postpectoral EO with two columns and four rows of electrocytes. EO dorsal groove extending approximately one to two orbital diameters before posterior border of eye. Scales present on mid-dorsal region of body. Scales above lateral line at midbody three to five [five] (N = 7). Scales below lateral line six to seven [six] (N = 7). Total anal-fin rays 137–156 [156] (N = 7). Caudal filament moderate. Precaudal vertebrae 15 (12 anterior; three transitional; N = 1). Pigmentation (Fig. 30 and Fig. 23C for colour of live specimen): Body background dark brown. Light tan oblique bands from nape to end of caudal filament (14–17 crossing dorsal region of body, counting from nape to last anal-fin ray). Head dark brown. Prominent series of more or less regularly spaced inverted U-shaped dark spots over pterygiophores, at margin of anal fin, separated by light margins. Pectoral-fin ray and inter-radial membrane hyaline. Anal-fin ray and inter-radial membrane hyaline. Electric organ discharge: Data available from eight specimens in type series, from the vicinity of Jenaro Herrera, Loreto, Peru. Hypopygus ortegai generates a tetraphasic EOD (Fig. 17) ranging in duration from 1.17 to 2.11 ms (mean 1.73, N = 7), and with a PPF ranging from 1.408 to 1.869 kHz (mean 1.661, N = 7). Mean pulse rate during the day ranges from 44.7 to 56.8 Hz (mean 50.3, mean CV 0.91, N = 8), and during the night from 59.2 to 65.5 Hz (mean 62.1, mean CV 2.87, N = 8).


HYPOPYGUS: PHYLOGENY AND TAXONOMIC REVISION Distribution: Hypopygus ortegai is known from small tributaries in the upper Amazon of Peru, near the towns of Iquitos and Jenaro Herrera, Loreto (Fig. 28). Ecology: Hypopygus ortegai occurs in small rainforest creeks – primarily in dense mats of tree roots along the edge of streams, especially in undercut banks. Stomach contents (N = 5) included a variety of autochthonous aquatic invertebrates – mostly larvae of Chironomidae, Trichoptera, Coleoptera, and Ephemeroptera, and some remains of small shrimps. Hypopygus ortegai occurs syntopically with H. lepturus. Whereas H. lepturus is found in groups of up to several dozen individuals, H. ortegai is usually only found in groups of no more than three or four individuals. Additionally, whereas H. lepturus is found in streams both under rainforest canopy and in open areas (e.g. cleared farmland), H. ortegai is restricted to streams under dense forest canopy. Etymology: The specific epithet, ortegai, is a patronym in honour of the Peruvian ichthyologist Hernán Ortega Torres, for his many contributions to Neotropical ichthyology and for his participation in the expedition that discovered this species. Remarks: Specimens of H. ortegai are unique amongst species of Hypopygus in having the third basibranchial ossified. Hypopygus ortegai is also the largest species of the genus. Although its maximum body length (126 mm) is exceeded by H. cryptogenes (150 mm, largely because of a very long caudal filament), its maximum live weight (3.6 g) exceeds by more than twofold the maximum live weight of all congeners (c. 1.5 g). Material examined: (114 specimens.) Holotype. Peru, Loreto, MUSM 35305, 107 mm (WC02.160104, female); unnamed stream, 2 km north of km 3.9 on road from Jenaro Herrera to Colonia Angamos, 04°53′01″S, 073°38′10″W; W. Crampton, R. Reis, F. Lima, H. Ortega. 16.i.2004. Paratypes. Peru, Loreto. MUSM 35306, 2, 101–114 mm (WC02.130104, female, 114 mm; WC03.130104, female, 101 mm); Quebrada Sapuenillo, c. 7 km E Jenaro Herrera on road from Jenaro Herrera to Colonia Angamos, Río Ucayali drainage, 04°54′26″S, 073°36′44″W; W. Crampton, R. Reis, F. Lima, H. Ortega, 13.i.2004. MUSM 38677, 2, 71–73 mm (WC46.110709, immature, 73 mm; WC47.110709, immature, 71 mm); forest stream near Jenaro Herrera, Río Ucayali drainage, 04°53′35″S, 073°39′06″W; W. Crampton, E. Correa, M. Aldea Guevara, J. Waddell, 11.vii.2009. MUSM 38678, 1, 65 mm (WC01.120709); forest stream near Jenaro Herrera, Río Ucayali drainage, 04°52′42″S,

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073°38′51″W. W. Crampton, E. Correa, M. Aldea Guevara, J. Waddell; 12.vii.2009. MUSM 38679, 5, 56–75 mm (WC01.140709, immature, 67 mm; WC02.140709, 71 mm, immature; WC04.140799, 70 mm, immature; WC13.140709, 56 mm, immature; WC14.140799, 75 mm, immature); forest stream near Jenaro Herrera, Río Ucayali drainage, 04°52′24″S, 073°38′49″W; W. Crampton, E. Correa, M. Aldea Guevara, J. Waddell, 14.vii.2009. MUSM 38680, 8, 73–79 mm (WC01.160709, 77 mm, immature; WC02.160709, 73 mm, immature; WC03.160799, 76 mm, immature; WC04.160709, 75 mm, immature; WC05.160709, 76 mm, immature; WC06.160709, 79 mm, immature; WC.08160799, 77 mm, immature); forest stream near Jenaro Herrera, Río Ucayali drainage, 04°52′45″S, 073°38′51″W; W. Crampton, E. Correa, M. Aldea Guevara, J. Waddell, 16.vii.2009. UF 148458, 1 73 mm (WC23.090104, immature); stream in forest c. 2 km north of Instituto de Investigaciones de la Amazonia Peruana (IIAP) field station (2.7 km east of Jenaro Herrera), c. 04°53′S, 073°39′W; W. Crampton, R. Reis, F. Lima, H. Ortega, 9.i.2004. UF 148524, 6, 83–118 mm (2 CS) [4 recorded: WC01.160104, immature, 92 mm (CS); WC03.160104, male, 118 m TL; WC04.160104, immature, 89 mm; WC05.160104, female, 98 mm]; same collecting data as holotype. Nontypes. Peru, Loreto. ANSP 167730, 1, 75 mm; Río Nanay, brook crossing left trail c. 20 min walk from Mishana, Río Nanay drainage, 05°53′S, 073°27′W. UF 176879, 1, 101 mm (CS); Río Nanay, 50 km 250° from Iquitos, 03°53′50″S, 073°40′01″W. MUSM 38681, 3, 75–82 mm (3 recorded for EODs); forest stream near Jenaro Herrera, Río Ucayali drainage, 04°54′26″S, 073°36′44″W. MUSM 38682, 1, 49 mm (1 recorded for EODs); forest stream near Jenaro Herrera, Río Ucayali drainage, 04°54′40″S, 073°39′29″W. MUSM 38683, 2, 84–103 mm (2 recorded for EODs); forest stream near Jenaro Herrera, Río Ucayali drainage, 04°53′54″S, 073°38′23″W. MUSM 38684, 3, 77–78 mm (3 recorded for EODS); forest stream near Jenaro Herrera, Río Ucayali drainage, 04°54′15″S, 073°36′53″W. MUSM 38685, 8, 73–87 mm (8 recorded for EODs); forest stream near Jenaro Herrera, Río Ucayali drainage, 04°54′26″S, 073°36′44″W. MUSM 38686, 69, 62–126 mm (69 recorded for EODs); forest stream near Jenaro Herrera, Río Ucayali drainage, 04°52′33″S, 073°38′13″W.

ACKNOWLEDGEMENTS The following provided access to specimens: M. Sabaj, J. Lundberg (ANSP); S. Schaeffer, B. Brown (AMNH); J. Armbruster, D. Werneke (AUM); O. Crimmen, J. Maclaine (BMNH); D. Catania (CAS-SU); M. Arraya


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Borges, M. Maldonado (CBF, UMSS); J. Friel, C. Dardia (CU); M. Rogers, P. Willink (FMNH); J. Maldonado-Ocampo (IAVHP), M. Retzer (INHS); L. Rapp Py-Daniel A. Canto, R. de Oliveira, M. Rocha (INPA); F. Provenzano (MBUCV-V); D. Taphorn (MCNG); R. Reis, Z. Lucena, J. Pezzi da Silva (MCP); K. Hartel, A. Holmes (MCZ); R. Causse, B. Parisi (MNHN); P. Buckup (MNRJ); W. Wosiacki (MPEG); S. Prada (MPUJ); H. Ortega (MUSM); F. Lima, J. Figueiredo, O. Oyakawa (MZUSP); S. Kullander, E. Ahlander, A. Silfvergrip (NRM); R. Winterbottom, M, Burridge, E. Holm (ROM); J. Albert, L. Page, R. Robins (UF); L. Queiroz (UFRO-I); D. Nelson (UMMZ); R. Vari, S. Jewett (USNM). The authors acknowledge the National Science Foundation (grants DEB–0614334 and DEB-0215388) and the University of Central Florida for funding. The following provided assistance with field collections: Instituto Mamirauá, J. Alves Oliveira, J. Ayres, W. Bentes Monteiro, W. Hamilton, P. Henderson, L. Queiroz, C. Nagamachi, J. Ready (Brazil), H. Ortega, M. Aldea Guevara, E. Correa Roldán (Peru), M. Arraya (Bolivia), J. Mol, K. Wang Tong You (Suriname), C. Montaña, N. Lovejoy, S. Willis, K. Lester (Venezuela), J. Albert (Peru and Bolivia), M. Richer-de-Forges (Bolivia and Suriname). L. Assakawa, M. Cartwright, J. Remo, M. Smith, and R. de Oliveira assisted with photography and artwork. For fruitful discussion we thank J. Albert, G. Arratia, R. Vari, and W. Wosiacki.

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APPENDIX 1 Phylogenetic character matrix comprising 47 characters for the examined species of Hypopygus and outgroups. Characters inapplicable to particular taxa are indicated by dashes. Characters numbers correspond to those in the text. Polymorphism is indicated by ‘?’. Character 11111111112 2222222223 3333333334 4444444 1234567890 1234567890 1234567890 1234567890 1234567

Taxon Gymnorhamphichthys G. rondoni Rhamphichthys R. marmoratus Steatogenys S. duidae Hypopygus H. cryptogenes H. hoedemani H. isbruckeri H. lepturus H. minissimus H. neblinae H. nijsseni H. ortegai

0000000000 0000000000 0001000000 0000000000 0110000 0000000000 0000000000 0001000001 0000000000 0000000 0000000001 1100000001 0000001000 0000000001 0000000 1100100001 1111101111 1100000001 1100?00111 1111111111 1100000001 1100000001 1100000001

APPENDIX 2 Cleared and genera and followed by the number stained, the information.

stained materials examined: the species names in this listing are an institutional catalogue number, of specimens cleared and countertotal length in mm, and locality

BRACHYHYPOPOMUS Brachyhypopomus brevirostris Steindachner. UF 176887, 2, 74–105 mm; Venezuela, Apure, Hato El Frio near Mantecal, Rio Guaratico drainage, Orinoco drainage, 04°00.349′N, 67°39.703′W. MCP 44605, 1, 374 mm (WC 06.010596, male); Brazil, Amazonas, Rio Tefé drainage, Lago Tefé, Ressaca do Cachorrinho, 03°20.13S, 64°42.16′W. MCP 44606, 3, 124–308 mm (WC13.180197, male, 308 mm; WC06.310197, immature, 175 mm; WC07.310197, immature, 124 mm); Brazil, Amazonas, Rio Tefé drainage, Lago Tefé, Cabeçeira do Lago Tefé, 03°36.92′S, 64°57.98′W. MCP 44758, 1, 257 mm (WC07.030597, immature); Brazil, Amazonas, Ressaca da Vila Alencar, near Boca do Lago Mamirauá, Mamirauá lake system, Rio Solimões floodplain, 03°07.70′S, 64°47.86′W. MCP 44759, 1, 47.7 mm (immature); Brazil, Amazonas, Rio Tefé drainage, Lago Tefé, Ressaca do Cachorrinho, 03°20.13S, 64°42.16′W.

1111001011 11111112–1 1111001001 1111101011 11111111–1 1111001001 1111001011 1111001011

0111001011 1111111011 0111001011 1111001011 1111111011 0101001111 0111001011 0111001011

0101000001 1011000111100000001 1110000111011000110100000001 1100011001 1100100001

0020111 1020111 0020111 1020111 1121111 0020111 0020111 0020111

Brachyhypopomus diazi Fernández-Yépez. UF 176888, 3, 80–107 mm (WC02.020403, female, 107 mm; WC06.020403, female, 96 mm; WC14.020403, female, 80 mm; Venezuela, Apure, Hato El Frio near Mantecal, Rio Guaratico drainage, Orinoco drainage, 04°00.349′N, 67°39.703′W. UF 174333, 4, 20–121 mm (WC05.210304, female, 100 mm; 06.210304, immature, 132 mm; WC09.210304, male, 121 mm; unrecorded 20 mm); Venezuela, Carobobo, Río Alpargaton 8 km west of Morón, Río Salado drainage; 10°27.976′ N 68°15.628′ W. Brachyhypopomus sp. nov. ‘WAL’, MCP 44741, 1, 146 mm (WC01.201296, immature); Brazil, Amazonas, Igarapé Repartimento, near Tefé, Rio Tefé drainage, 03°24.46′S, 64°44.17′W. MCP 44742, 1, 104 mm (WC07.040598, female), MCP 44607, 1, 150 mm (WC05.200598, female); Brazil, Amazonas, Lago Periquito Comprido, Rio Solimões-Japurá confluence floodplain; 03°04.89′S, 64°46.80′W. MCP 44649, 2, 140–185 mm (WC04.020698, male, 185 mm; 05.020698, female, 140 mm); Brazil, Amazonas, Lago Curuçá Comprido, Rio Solimões-Japurá confluence floodplain; 03°05.50′S, 64°48.98′W. MCP 44743, 2, 103–124 mm (01.130799, immature, 124 mm; 17.130799, 1, 103 mm); Brazil, Amazonas, Rio Tefé, Rio Tefé drainage, 03°37.718′S, 64°59.057′W. MCP 44744, 1, 141 mm; Brazil, Amazonas, Amazonas, Ressaca da Vila Alencar, near Boca do Lago


HYPOPYGUS: PHYLOGENY AND TAXONOMIC REVISION Mamirauá, Mamirauá lake system, Rio Solimões floodplain, 03°07.70′S, 64°47.86′W. Brachyhypopomus sp. indet. MCP 44760, 2, 37.2– 37.4 mm; MCP uncatalogued, 1, 74 mm; Brazil, Amazonas, Amazonas, Ressaca da Vila Alencar, near Boca do Lago Mamirauá, Mamirauá lake system, Rio Solimões floodplain, 03°07.70′S, 64°47.86′W.

GYMNORHAMPHICHTHYS Gymnorhamphichthys hypostomus Ellis, FMNH 100744, 1, 183 mm; Venezuela, Barinas, Rio Suripa between pumping station of Hato Mercedes and Boca Rio Anaro. Gymnorhamphichthys rondoni (Miranda-Ribeiro). MCP 44603, 1, 128 mm (WC01.240899, immature); Brazil, Amazonas, Igarapé Repartimento, tributary of Lago Tefé, Rio Tefé drainage, 03°24.5′S, 64°44.2′W.

HYPOPOMUS Hypopomus artedi Kaup, UF 176889, 2, 225–242 mm (WC05.070307, male, 242 mm; WC06.070307, male, 225 mm); Suriname, Brokopondo, Marshal creek, affluent of Suriname Riviere, on Affobaka road from Paranam refinery to Brokopondo reservoir, 05°14.693′N, 55°06.073′W. NRM 32247, 1, 31.4 mm. French Guiana, Cayenne, tributary of Oyapock River.

HYPOPYGUS Hypopygus cryptogenes (Triques), MZUSP 30088, 1, 147 mm; Brazil, Amazonas, near Rosa Maria, Rio Negro drainage, 0°19′S 065°7′W. INPA 29373, 1, 99.4 mm. Brazil, Amazonas, near Novo Airão, 01.8016700°S, 061.6462800°W. Hypopygus hoedemani sp. nov., MZUSP 81488, 1, 42.7 mm; Brazil, Amazonas, Rio Tiquié, Rio Negro drainage, 00°15′55″N, 069°58′16″W. INPA 33948, 1, 49 mm; Brazil, Amazonas, Rio Preto da Eva drainage, 02°47′35″S, 059°38′21″W. Hypopygus isbruckeri sp. nov., UF 148539, 3, 64.0– 90.0 mm. Venezuela, Amazonas, near San Fernando de Atabapo, 03°58′50.2″N, 067°36′28.1″W. Hypopygus lepturus, Hoedeman, UF 176882, 1, 92 mm (WC09.050307), Suriname, Para, Kola Kreek, c. 6 km west of village of Zanderij and Johan Adolf Pengel International Airport, Para Rivier drainage, Suriname Rivier drainage, 05°27.147′; N55°14.701′W. UF 176884, 1, 91 mm (WC25.090307), Suriname, Marowijne, stream on road from Paramaribo to French Guyana, Cottica Rivier, Commewijne Rivier, 05°35.210′N, 54°17.113′W. FMNH 96506, 3, 64.4– 77.6 mm, Ecuador, Sucumbios, tributary of Río Cuyabeno, near Marian, Río Aguarico, Río Napo drainage,

1155

c. 0°2′S, 076°20′W. MCP 44755, 3, 30.0–46.5 mm. Brazil, Amazonas, Igarapé Baré, tributary of Lago Amanã, municipality of Maraã, Rio Japurá drainage, 02°26.28′S, 064°43.5′W. Hypopygus neblinae, Mago-Leccia, UF 148540, 3, 75–80 mm. Venezuela, Amazonas, near San Fernando de Atabapo, 03°55′59.0″N, 067°36′34.2″W. Hypopygus nijsseni; MCP 44737, 2, 72–73 mm; Brazil, Amazonas, Igarapé Repartimento, tributary of Lago Tefé, Rio Tefé drainage, 03°24.5′S, 064°44.2′W. Hypopygus ortegai sp. nov., UF 176879, 1, 101 mm; Peru, Loreto, Río Nanay, 50 km from Iquitos, 03°53′50′S, 073°40′01′W. UF 148524, 1, 92 mm (WC 01.160104, immature), Peru, Loreto, stream c. 2 km north of km 3.9 on Jenaro Herrera – Colonia Angamos road, 04°53.021′S, 73°38.160′W. Hypopygus minissimus, new species, UF 148533, 3, 42.0–42.0 mm (WC41.120304, female 42 mm; female, 42 mm; WC 29.150304, immature, 42 mm; unrecorded, female 43 mm). Venezuela, Amazonas, near San Fernando de Atabapo, 03°55.984′N, 067°36.57′W.

MICROSTERNARCHUS Microsternarchus bilineatus Fernández-Yépez. UF 176886, 5, 75–111 mm; Venezuela, Amazonas, Caño Cascadura, near San Fernando de Atabapo, 04°00.349′ N, 067°39.703′W. MCP 44653, 3, 23–44 mm; Brazil, Amazonas, Igarapé Repartimento, tributary of Lago Tefé, Rio Tefé drainage, 03°24.5′S, 064°44.2′W.

RHAMPHICHTHYS Rhamphichthys marmoratus, Castelnau, MCP 44756, 1, 159 mm (WC01.290594, immature), Brazil, Amazonas, Boca do Igarapé Xidarini, Lago Tefé, Rio Tefé drainage, 03°21.62′S, 064°41.89′W. Rhamphichthys cf. mamoratus, MCP 44604, 2, 43.4–43.4 (WC01.020195, immature, 43.4 mm; WC02.020195, immature, 43.4 mm); Brazil, Amazonas, Lago Juruazinho, near confluence of Rio Japurá and Rio Solimões, 03°02.58′S, 064°51.01′W. Rhamphichthys lineatus Castelnau, MCP 44757, 1, 286 mm (WC36.240200, immature); Brazil, Amazonas, Praia Caborini, confluence of Rio Solimões and Rio Japurá, 03°09.14′S, 64°47.06′W.

STEATOGENYS Steatogenys duidae, MCP 31957 (WC01.300600), 1, immature, 104 mm; MCP 31957 (WC02.300600), 1 immature, 100 mm; Brazil, Amazonas, near Tefé, 03°24.46′S, 064°44.17′W. UF 148524, 1, 90 mm. Venezuela, Amazonas, near San Fernando de Atabapo town centre, 03°55′59.0″N, 067°36′34.2″W.


16 8.7

MCP 44653 MCP 44653

14.2 16.1

11.3 12.4

NRM 32247 MCP 44653

MCP 31957 MCP 31957

14.4 13.6 28.3

MCP 44760 MCP 44760 MCP 44603

15.3

17.8

MCP uncat.

MCP 44604

11.4 9.9 10.3 9.2 12.3 12.3 13.2

BC mm

MZUSP 81488 MCP 44755 MCP 44755 MCP 44755 UF 148533 UF 148533 MCP 44759

Catalogue number

85 81.5

43.4

44 23.3

31.4 35.6

37.2 37.7 122

74.0

42.7 30.0 46.5 32.1 42.0 43.0 47.7

TL mm

ossified ossified

unossified

unossified unossified


unossified unossified ossified

ossified

absent unossified unossified unossified absent absent unossified

NC

ossified ossified

unossified


? unossified


ossified

two ossified three unossified three unossified three unossified one ossified one ossified unossified

MC

present present

present

absent absent

absent absent

absent absent present

absent

absent absent absent absent absent absent absent

V

large large

narrow

narrow narrow

narrow narrow

large large narrow

narrow

narrow narrow narrow narrow narrow narrow large

ADF

ossified ossified

absent

ossified ossified

ossified ossified

ossified ossified ossified

ossified

absent absent absent absent absent absent ossified

PASOC

ossified ossified

absent

ossified ossified

ossified ossified


ossified

absent unossified unossified unossified ossified ossified ossified

SOC

ossified ossified

ossified

ossified absent

absent ossified


ossified

absent ossified ossified ossified absent absent ossified

IOCA

ossified ossified

absent

unossified absent

absent unossified


ossified

absent absent absent absent absent absent unossified

IOC6

ossified partially ossified partially ossified ossified ossified

ossified ossified


ossified

absent ossified ossified ossified ossified ossified ossified

ESC

ossified ossified

ossified

ossified ossified

ossified ossified


ossified

absent unossified unossified unossified absent absent ossified

POCL

ossified ossified

ossified

unossified absent

ossified unossified


ossified

absent absent absent absent absent absent ossified

POSC

Abbreviations: ADF, anterior dorsal fontanel; BC, body cavity; ESC, extrascapular canals; IOCA, aperture of the infraorbital canal; IOC6, sixth infraorbital canal bone; MC, mandibular canal; NC, nasal laterosensory canal; PASOC, parietal branch of the supraorbital canal; POCL, postotic canal of the lateral line; SOC, supraorbital canal; TL, total length; uncat., uncatalogued; V, vomer.

Rhamphichthys marmoratus Steatogenys duidae S. duidae

H. hoedemani H. lepturus H. lepturus H. lepturus H. minissimus H. minissimus Brachyhypopomus brevirostris Brachyhypopomus sp. indet. B. sp. indet. B. sp. indet. Gymnorhamphichthys rondoni Hypopomus artedi Microsternarchus bilineatus M. bilineatus M. bilineatus

Species

Ontogenetic comparative data of some reductive characters in miniaturized Hypopygus species (Hypopygus hoedemani, adult; Hypopygus lepturus, juvenile; and Hypopygus minissimus, adult), and in available juveniles of nonminiaturized species of Rhamphichthyoidea

APPENDIX 3

