Two New Mexican Endemic Species of Iresine ...

Two New Mexican Endemic Species of Iresine (Amaranthaceae) Author(s): Silvia Zumaya , Hilda Flores-Olvera , and Thomas Borsch Source: Systematic Botany, 38(2):434-443. 2013. Published By: The American Society of Plant Taxonomists URL: http://www.bioone.org/doi/full/10.1600/036364413X666633

BioOne (www.bioone.org) is a nonprofit, online aggregation of core research in the biological, ecological, and environmental sciences. BioOne provides a sustainable online platform for over 170 journals and books published by nonprofit societies, associations, museums, institutions, and presses. Your use of this PDF, the BioOne Web site, and all posted and associated content indicates your acceptance of BioOne’s Terms of Use, available at www.bioone.org/page/terms_of_use. Usage of BioOne content is strictly limited to personal, educational, and non-commercial use. Commercial inquiries or rights and permissions requests should be directed to the individual publisher as copyright holder.

BioOne sees sustainable scholarly publishing as an inherently collaborative enterprise connecting authors, nonprofit publishers, academic institutions, research libraries, and research funders in the common goal of maximizing access to critical research.

Systematic Botany (2013), 38(2): pp. 434–443 © Copyright 2013 by the American Society of Plant Taxonomists DOI 10.1600/036364413X666633

Two New Mexican Endemic Species of Iresine (Amaranthaceae) Silvia Zumaya,1 Hilda Flores-Olvera,1,3 and Thomas Borsch2 1

Departamento de Botańica, Instituto de Biologıá. Universidad Nacional Autońoma de Me´xico. Apartado Postal 70-233, C. P. 04510 Me´xico, D. F. Me´xico. 2 Botanischer Garten und Botanisches Museum Berlin-Dahlem und Institut fu¨r Biologie, Freie Universita¨t Berlin, Dahlem Center of Plant Sciences, Ko¨nigin-Luise-Straße 6-8, 14195 Berlin, Germany. 3 Author for correspondence ([email protected]) Communicating Editor: Lynn Bohs Abstract—Iresine rzedowskii Zumaya, Flores Olv. & Borsch and I. valdesii Zumaya, Flores Olv. & Borsch are described, illustrated, and compared to morphologically similar species. In addition, pollen SEM micrographs and distribution maps are provided for the new species. Iresine rzedowskii is a shrub with long clambering stems, the younger ones reddish with conspicuous lenticels and the older ones with suberose cortex. It is the only species of Iresine that has pollen grains with a foveolate tectum. Iresine valdesii is also a shrub but with stiff erect branching and small, perennial coriaceous leaves. The synflorescences of staminate plants are solitary, very small, usually once-branched thyrsoid structures while those of pistillate plants are very different, with paracladia appearing terminal on most branches and erect, up to 13 cm long, and two to three times branched. Both species are restricted to Mexico. Iresine rzedowskii ranges from northwestern Chihuahua to northern Oaxaca, while I. valdesii is endemic to central and southeastern Puebla. Keywords—Caryophyllales, dioecious plants, endemism, Gomphrenoideae, Mexico, pollen morphology.

Iresine P. Browne belongs to subfamily Gomphrenoideae of the Amaranthaceae. This subfamily was described by Schinz (1893) based on its unilocular anthers and was confirmed as being monophyletic with molecular data (Mu¨ller and Borsch 2005; Sańchez del-Pino et al. 2009). Iresine was circumscribed in a very broad sense in the pre-phylogenetic literature by a number of authors (Dietrich 1839; MoquinTandon 1849; Hooker 1880; Standley 1917) who included within it the unrelated genera Hebanthe Mart. and Pedersenia Holub ( Trommsdorffia Mart. nom. illeg. because of an earlier homonym). These genera of neotropical lianas were separated from Iresine mainly based on their distinctive metareticulate pollen morphology (Borsch 1995, 1998; Borsch and Pedersen 1997), characterized by strongly vaulted mesoporia with the lumina of the metareticulum corresponding to the apertures (Borsch and Barthlott 1998). In both Hebanthe and Pedersenia, microspines are arranged in a single row in the distal parts of the mesoporia. On the other hand, all members of Iresine sensu stricto have pantoporate pollen with moderately vaulted mesoporia and numerous evenly spread microspines (Iresine type pollen sensu Borsch 1998). Molecular phylogenetic analyses show that this narrow circumscription of Iresine, also adopted here, matches with an Iresine clade (Sańchez del-Pino et al. 2009; Borsch et al. unpubl. data) that is sister to all remaining Gomphrenoideae. The species of Iresine are variable in habit, being trees, shrubs, lianas or annual herbs. Although many species are adapted to dry and sunny habitats, Iresine is exclusively C3, unlike other lineages of the Amaranthaceae (Sage et al. 2007). The majority of species are dioecious, but a few are hermaphroditic or gyno-dioecious. Leaves are opposite (except in I. alternifolia S. Watson and I. leptoclada (Hook. f.) Henr. & S. D. Sundb.), and the different species exhibit a variety of trichome types. The flowers are short-pedicelled, and the subtending bract and bracteoles remain on the rachis when the flowers fall. The tepals of pistillate and bisexual flowers develop a conspicuous tuft of parallel hairs at maturity, facilitating dispersal. The filaments alternate with pseudostaminodia. As in other Gomphrenoideae, Iresine has polytelic synflorescences composed of paracladia (Borsch and Pedersen 1997; Acosta et al. 2009) but descrip-

tions in the literature often use more superficial terminology such as the panicle-like inflorescences mentioned by Standley (1916). Iresine is a neotropical genus with approximately 45 species ranging from the southern United States to southern South America and the Caribbean. Mexico is the center of diversity with 27 species currently recognized (Zumaya 2008), of which more than 55% are endemic. Some of the species have a very wide distribution such as I. diffusa Humb. & Bonpl. ex Willd. (occurring in almost the complete range of the genus) or I. latifolia (M. Martens & Galeotti) Benth. & Hook. (ranging from the state of Baja California Sur in Mexico to Panama). Other species, such as I. rotundifolia Standl. Standl. (Tehuacań-Cuicatlań Valley) or I. alternifolia S. Watson (Baja California Sur and Sonora) have very restricted ranges. Most endemic species of Iresine grow in specific habitats such as in pine-oak forests (I. ajuscana Suess. & Beyerle), arid tropical scrub (e.g. I. alternifolia S. Watson, I. leptoclada (Hook. f.) Henr. & S. D. Sundb.), tropical evergreen forest (I. arbuscula Uline & W. L. Bray), tropical deciduous forest (I. discolor Greenm. and I. pringlei S. Watson), or even sand dunes (I. flavescens Humb. & Bonpl. ex Willd.). In the course of extensive taxonomic and phylogenetic work on Iresine, two new Mexican endemic species have been found, which are described in this paper.

Materials and Methods Survey of Herbarium Specimens—During the course of this study nearly 4,000 specimens were examined from the following herbaria: ASU, B, CIIDIR, CHAPA, ENCB, F, FCME, GH, IBUG, IEB, K, M, MEXU, NY, OAX, RSA-POM, SERO, XAL, UC, and US. Field Collections—Plants were studied within their natural environment to examine characters not well documented in dried specimens and collected in the field to obtain complete material including vegetative parts (e.g. lower stems, bark, habit, etc.) and individuals of both sexes from single populations. In addition, field work was useful in characterizing the vegetation types in which the respective species were growing. Scanning Electron Microscopy—Pollen grains were sampled from herbarium specimens. Air dried grains were directly mounted on LeitTabs (Plano GmbH, Marburg, Germany) and coated with gold (ca. 25 nm) using a Sputter Coater (Balzers Union SCD 040, Balzers GmbH,

434

ZUMAYA ET AL.: NEW SPECIES OF IRESINE

Iresine rzedowskii Zumaya, Flores Olv. & Borsch, sp. nov.— TYPE: MEXICO. Michoacań: Mun. Quiroga, 2 km al NE de Capula rumbo a Quiroga, carretera 15 MoreliaQuiroga, 2,204 m, 19 390 19.400 N, 101 210 2200 W, 13 Feb 2005, Borsch, Zumaya & Flores 3788a [staminate plant], (holotype: MEXU; isotypes: B, IEB, ENCB, MEXU, US). Paratype: Borsch, Zumaya & Flores 3788b [pistillate plant], (B, IEB, MEXU, US). Iresine hartmanii var. gentryi f. palmeri Suess. Mitt. Bot. Staatssamml. Mu¨nchen 4: 108–109. 1952. TYPE: MEXICO. Durango: Mun. Tejamen, 21–27 Aug 1906, Palmer 64 (lectotype: M [here designated]; isolectotypes, F, K [2 sheets], US).

+ +

+

+

+

Diagnosis [based on a staminate plant]. Differs from other scandent species such as Iresine interrupta or I. ajuscana by its solid stems with conspicuous lenticels (younger), or with suberose cortex (older); by the uppermost branches in synflorescences subtended by dark brown bract-like ovate to triangular scales 0.6–0.8 mm long and basally carinate bracts with distinct midveins, the bracts brown in color but membranous to hyaline at the margins; and by the punctatefoveolate tectum of the pollen grains. Dioecious perennial shrubs. Stems scandent or clambering, 0.6–7 m tall, dark green to dark reddish-brown in the terminal parts, the younger ones reddish with numerous conspicuous lenticels, glabrous or subglabrous, the older stems with a suberose cortex. Leaves opposite, the blades lanceolate to ovate-lanceolate, 2.5–9.2 1–4.5 cm, thin to almost membranaceous, cuneate at base, narrowly decurrent into the petiole, acuminate to long acuminate at the apex, subglabrous to very sparsely pubescent with 0.3–0.5 mm long, uniseriate, appressed trichomes; petioles 0.3–1 cm long. Synflorescences of pistillate and staminate plants similar, branched up to the third order with a dominant principal 18–28 cm, consisting of 5–14(–16) flowers axis, 15–75 aggregated into conical to subglobose heads (paracladia), the axis densely villous with trichomes 0.2–0.4 mm long; heads 0.3–0.4(–0.7) cm high, on 3–8 mm long pedicels, subtended by dark brown bract-like scales with hyaline margins; other inflorescence branches subtended by small herbaceous leaves, glabrous, the terminal parts below heads usually with short trichomes. Staminate flowers with bracts and bracteoles subequal in length, reaching to about half the length of tepals; bracts ovate to triangular, 0.6–0.8 mm long, somewhat carinate at base, the midvein and central part distinct, brown, membranous to hyaline at the margins, sparsely pubescent, shortly mucronate at apex; bracteoles ovate to suborbiculate, 0.7–0.9 mm long, membranous to hyaline, rounded to cleft at apex, sparsely pubescent; tepals (of mature flowers) ovate to ovate-oblong, or narrowly ovateoblong (the inner two), the outer tepals 1.9–2.2 0.8–1 mm, the middle 1.6–1.8 0.5–1 mm, the inner 1.5–1.6 0.3–0.7 mm, subcoriaceous to membranaceous at the margins, yellowishbrown, rounded to acute (the inner) at apex, 1-veined, the vein extending to about 3/4 of the length of the tepal, villous abaxially with 0.4–0.7 mm (in the upper part with 0.1–0.3 mm) long, white, uniseriate, irregularly curved trichomes; filaments

shortly connate (for about 20% their length), 0.9–1.2 mm long, the pseudostaminodia subulate to narrowly triangular, 0.2 – 0.3 mm long, papillose. Pistillate flowers with bracts shorter than the bracteoles, these subequal to the tepals; bracts ovate to suborbiculate, 0.7 – 1.4 mm long, somewhat carinate at base, the midvein reaching to the apex, yellowish brown, membranous to hyaline at the margins, glabrous to pilosevillous at the apex; bracteoles broadly ovate to reniform, 1.2 – 1.7 mm long, membranous to hyaline, rounded to cleft at apex, glabrous to sparsely villous at the apex; tepals (of mature flowers) ovate to broadly ovate or narrowly ovate (the inner two), the outer tepals 1.6 – 1.8 0.9 – 1 mm, the 0.5 – 1 mm, the inner 1.5 – 1.8 0.5 – 1 mm, middle 1.6 – 2 subcoriaceous to membranaceous at the margins, greenish to brown, acute to rounded (outer) at apex, 3(5)-veined, the veins extending to about 3/4 the length of the tepal, villous abaxially with 0.5 – 3 mm long trichomes in the upper part; long trichomes at maturity white, finely undulate, up to twice as long as tepals. Ovary subglobose, 0.4 – 0.5 mm long, the style inconspicuous, the stigmas narrowly cylindrical, 0.2–0.3 mm. Seeds subglobose, ca. 1 mm in diameter, yellowish brown to brownish. Pollen spheroidal, (15 –)16– 18.5 mm in diameter, with 18–23 apertures; pores 2–2.4 mm in diameter, all of equal size, the ektexinous bodies 10–14, cone-shaped with acute tips, well separated and ± evenly spaced; mesoporia broadly vaulted, 2.8–3.5 mm wide, the tectum punctate-foveolate, with perforations 250–500 nm in diameter, often ovate or rounded to triangular, with 5–7 perforations per 10 mm2, ± evenly spaced, the spinules narrowly cone-shaped with acute tips, 200–240 nm high, 180–200 nm in diameter at base, with 21–27 spinules per 10 mm2, irregularly spaced. Figures 1 , 2 , 3a.

+

Taxonomic Treatment

435

+

Wiesbaden, Germany) for 60 sec. with 30 mA. Specimens were then analysed with a Cambridge S200 scanning electron microscope.

+

2013]

Additional Specimens Examined—MEXICO: Chihuahua, Mpio. Urique, along rıó Urique, NW of Humira bridge, near junction with Arroyo Humira on N side of river, 9–10 Jan 1981, Bye 10160 (MEXU). Durango, Mpio. Topia, arroyo La Chorrera, 14 Mar 1987, Acevedo 301 (CIIDIR, MEXU); Mpio. Pueblo Nuevo, arroyo de La Puerta, 5.5 km. al E de La Libertad, brecha al Huizache, 9 Mar 1985, Tenorio 8182 (MEXU). Guanajuato, Mpio. Aca´mbaro, a la entrada de Aca´mbaro, loma de lado derecho carretera Maravatıó-Aca´mbaro, 16 Feb 2005, Borsch 3796 (B, IEB, MEXU). Guerrero, Mpio. Iguala de la Independencia, canõn de La Mano, entre Los Amates y El Naranjo, 10 km. al N de Iguala por el ferrocarril, barranca de La Vieja, 7 Feb 1987, Catalań 643 (CHAPA, FCME, MEXU, OAX); Mpio. Eduardo Neri, 2.5 km. al N de Xochilapa, 24 Nov 1990, Gual 243 (FCME). Jalisco, Mpio. Zapotitlań de Vadillo, faldas del volcań de Colima, 19 Mar 1976, Domıńguez 31 (IBUG); Mpio. Mezquitic, rancho Minillas, 15 km. al NE de Mezquitic, 26 Jan 1991, Flores 2578 (CHAPA); Mpio. Concepcioń de Buenos Aires, 7 km. al SE de Concepcioń de Buenos Aires, por el camino a El Valle Florido, 22 Feb 1989, Meńdez 44 (IBUG); Mpio. Talpa de Allende, 17 km al S de Talpa sobre la carretera a La Cuesta, 9 Mar 1995, Panero 5603 (IEB, MEXU); Mpio. Jocotepec, cerro Grande al “N” de Jocotepec, 17 Jan 1987, Reyna 267 (IBUG, XAL); Mpio. Tapalpa, El Salto, a 9 km. de Tapalpa, 4 Mar 1981, Sańchez 37 (IBUG); Mpio. Quitupan, al N de Quitupan, 5 Feb 1982, Zuń˜iga s. n. (IBUG). Michoacań, Mpio. Quiroga, 2 km. al NE de Capula rumbo a Quiroga, carretera 15 Morelia-Quiroga, 13 Feb 2005, Borsch 3788 (B, IEB, MEXU); Mpio. Indaparapeo, entrada a San Lucas Pıó, rumbo a Maravatıó, 13 Feb 2005, Borsch 3791 (B, IEB, MEXU); Mpio. Maravatıó, 10 km al NE de la desviacioń a Maravatıó carretera 125 Morelia-Maravatıó, a unos metros del Balnerio Las Adjuntas, 15 Feb 2005, Borsch 3793 (B, IEB, MEXU); Mpio. Tzintzuntzan, Ichupio, 1 Apr 1979, Caballero 936 (IEB, MEXU); Mpio. Acuitzio, cerca de Acuitzio del Canje, 2 Mar 1986, Dıáz 2084 (IEB, MEXU); Mpio. Morelia, canãda del rıó Grande, cerca de Cointzio, 26 Abr 1992, Dıáz 6941 (IEB, MEXU); Mpio. Erongarıćuaro, cerro Peloń, al N de la hacienda de Charahueń, 18 Jan 1986, Espinosa 2062 (CIIDIR, ENCB, IEB, MEXU); Mpio. Villamar, entre Litigio y Coameao Chico, 3 Mar 1987, Garcıá 1752 (IEB); Mpio. Zacapu, W de Santa Gertrudis, 13 Feb 1988, Grimaldo 22 (IEB, MEXU); Mpio. Zinapećuaro, arroyo Santa Teresa, 6 km al S de La Galera, 25 Jan 1989, Jasso 817 (IEB, MEXU); Mpio. Huaniqueo, E del pedregal pequenõ, 300 m al SW de Tendeparacua, 1 May 1993, Silva-Saénz 701

436

SYSTEMATIC BOTANY

[Volume 38

Fig. 1. Iresine rzedowskii Zumaya, Flores Olv. & Borsch. a–h. Staminate plant. a. Habit. b. Old stem with suberose cortex. c. Synflorescence. d. Paracladia. e. Mature flower. f. Tepals. g–h. Androecium and pistillode. i–n. Pistillate flower. i–j. Mature flower. k. Tepals. l. Gynoecium with staminodia. m. Fruit. n. Seed (a–h from T. Borsch et al. 3788a; i–n from T. Borsch et al. 3788b).

2013]


437

Fig. 2. Iresine rzedowskii Zumaya, Flores Olv. & Borsch. at the type locality. A. Habit. B. Old stem with suberose cortex. C. Staminate synflorescence. D. Pistillate synflorescence.

438

Fig. 3.

SYSTEMATIC BOTANY

[Volume 38

SEM micrographs of pollen grains from the type specimens. a. Iresine rzedowskii. b. Iresine valdesii.

(IEB, XAL); Mpio. Pa´tzcuaro, 4 km. west of Pa´tzcuaro along MEX 14, lower slopes of cerro El Estribo, ca. 300 m south of the highway, 10 Mar 2002, Steinmann 2364 (IEB, MEXU). Nayarit: Mpio. Jala, 15 km. al NE de Jalpa, volcań el Ceboruco, 12 Abr 1990, Flores 1904 (XAL). Oaxaca: Mpio. San Lorenzo Victoria, La Loma 5 km al W de San Jorge Nuchita hacia Yucayachi, 7 Feb 1993, Calzada 18294 (MEXU); Mpio. Santos Reyes Tepejillo, 3 km de Santos Reyes Tepejillo, senda para Las Cuevas del Diablo y rıó Boqueroń, 17 Mar 1998, Calzada 22453 (MEXU); Mpio. Santo Domingo Tonala´, de Los Limoncillos a Agua Escondida, 10 Dic 2008, Torres-Hernańdez 803 (MEXU, SERO). Puebla, Mpio. Puebla, Cerro San Isidro, 18 Dic 1942, Miranda 2540 (MEXU); Mpio. Tepejı´ de Rodrı´guez, el Naranjo, 4 km al NE de Todos Santos Almolonga, Apr 2004, Mota-Cruz 387 (MEXU); Mpio. Molcaxac, Molcaxac, puente natural del rıó Atoyac, 22 Mar 1970, Weber 141 (ENCB). Quere´taro, Mpio. Corregidora, el Batan, 8 Mar 1981, Arguëlles 1537 (MEXU); Mpio. Humilpan, Los Cues, ca. 2000 m, 4 Feb 1983, Arguëlles 2044 (ENCB, MEXU). Sinaloa, Mpio. San Ignacio, San Javier, terrenos de Balboa, sin fecha, Gonza´lez-Ortega 5115 (CHAPA).

Etymology—Iresine rzedowskii is named in honor of Dr. Jerzy Rzedowski Rotter, recently retired from the Instituto de Ecologıá, Pa´tzcuaro, Michoacań, in recognition of his contributions to the knowledge of the Mexican flora. Distribution and Habitat—Iresine rzedowskii is an endemic Mexican species ranging from the state of Chihuahua along the Sierra Madre Occidental through the mountains of central Mexico south to the northwestern part of the state of Oaxaca (Fig. 4) at 1,145–2,500 m in elevation. Most specimens were collected in tropical deciduous forest, arid tropical scrub, or in Quercus L. or Pinus L. dominated forest types. Often the species grows in small woody patches within grazed areas where it can benefit from the early phases of secondary succession. Phenology—Flowering and fruiting from December to July. Vernacular Names—Iresine rzedowskii is known as “kurikua” in Michoacań (Caballero 936), and as “hierba del Arlomo” in Jalisco (Dominguez 31). Conservation Status—The species is widely distributed from northwestern to southern Mexico, frequently growing in a rather wide spectrum of woody vegetation types, and

falls under the category of Least Concern (LC), following IUCN (2001) and IUCN Standards and petitions Working Group (2008) criteria. Iresine rzedowskii has been extensively collected but in herbaria has been often misidentified as other species such as I. angustifolia Euphr., I. discolor, I. grandis, I. interrupta Benth., and I. nigra Uline & W. L. Bray. The long scandent to climbing habit of I. rzedowskii bears some similarity to I. interrupta, I. ajuscana, I. hebanthoides Suess., and I. palmeri (S. Wats.) Standl. The latter two species, however, are true climbers with the upper part of stems often winding around other plants. The pollen of I. rzedowskii is of the Iresine type as described in Borsch (1998) but is unique in the genus due to its large tectum perforations (Fig. 3a). The same tectum morphology was observed in the specimen Palmer 64, a staminate plant and the type of I. hartmanii var. gentryi f. palmeri Suess. Pollen morphology therefore helped to clarify the identity of the latter taxon. Suessenguth (1952) described Iresine hartmanii var. gentryi f. palmeri based on inflorescences pressed as herbarium specimens that have a superficial resemblance to I. hartmanii Uline. Both I. hartmanii and I. rzedowskii have numerous small globular heads of flowers and tepals with a whitish indumentum. However, Suessenguth never saw the plants in the field and thus did not know the strikingly different habit and older stems with a suberose cortex (Figs. 1, 2). In the absence of any later revision or complete keys to the genus, Iresine hartmanii var. gentry f. palmeri was never mentioned again in the literature. Another specimen of E. Palmer 64 (NY) has both a different date (April 21- May 18, 1906) and locality (Durango, San Ramon), and is therefore not considered as an isolectotype of Iresine hartmanii var. gentry f. palmeri. Iresine valdesii Zumaya, Flores Olv. & Borsch, sp. nov.—TYPE: MEXICO: Puebla, Mun. Chapulco, entre el km. 65 y 66 de

2013]


439

Fig. 4. Distribution of Iresine rzedowskii (squares) and I. valdesii (triangles).

+

+

+

Diagnosis [based on a pistillate plant]. Differs from Iresine rotundifolia by the habit with stiff erect stems that are richly branched from the base, the coriaceous cauline leaves, glabrous or slightly tomentulose above, but densely villoustomentose below; by pistillate flowers in two to three times branched thyrsoid structures (paracladia), arranged in termi2.5–3 cm, upright, narrowly cylindrical nal, leafless, 7–13 synflorescences; and by the densely tomentose axis with trichomes 0.3–0.8 mm long. Dioecious perennial shrubs. Stems erect, richly branched from the base, 0.3–2.5 m tall, brown, dark gray to grayish, glabrous to densely tomentose in upper parts with white to yellow, uniseriate trichomes (these also on leaves, bracts and bracteoles). Leaves opposite, the blades ovate to suborbicular, 1–2.4 1–1.4 cm, coriaceous, rounded at base,

acute to mucronulate at the apex, glabrous or slightly tomentulose along veins above, densely villous-tomentose below with 0.1–0.6 mm long trichomes, the blade between first order lateral veins slightly vaulted and veins prominent at lower surface; sessile. Synflorescences of pistillate and staminate plants different; pistillate flowers loosely aggregated into subglobose paracladia consisting of (2–)4–10(–12) flowers, these arranged in leafless, 7–13 2.5–3 cm, upright, narrowly cylindrical, two to three times branched thyrsoid structures with a dominant principal axis; axis densely tomentose with trichomes 0.3–0.8 mm long, the paracladia subtended by yellowish brown bract-like scales sometimes with hyaline margins; staminate flowers aggregated into subglobose to short cylindrical paracladia consisting of 6–12 1.3–1.8 cm, one flowers, these arranged in leafless, 1.5–3 (to rarely two) times branched thyrsoid structures appearing mostly terminal on short branches. Staminate flowers with bracts and bracteoles subequal in length to slightly shorter than the tepals; bracts ovate to suborbicular, 1.5–1.6 mm long, not carinate at base, lightly veined, yellowish brown to dark brown, sometimes red, membranous to hyaline at the

+

la carretera Esperanza-Tehuacań, 4 km. al S del Fresnal, tramo Esperanza-Azumbilla, 2,300 m, 18 420 11.700 N, 97 240 21.400 W, 17 Mar 2007, Zumaya, Flores, Ochoterena & Borsch 72b [pistillate plant] (holotype: MEXU; isotypes: B, ENCB, IEB, MEXU, US). Paratype: Zumaya, Flores, Ochoterena & Borsch 72a [staminate plant] (B, IEB, MEXU).

440

SYSTEMATIC BOTANY

[Volume 38

Fig. 5. Iresine valdesii Zumaya, Flores Olv. & Borsch. a-h. Pistillate plant. a. Branch. b. Paracladia c. Mature flower. d. Bract and bracteoles. e. Tepals. f. Gynoecium with staminodia. g. Fruit. h. Seeds. I–m. Staminate plant. i. Paracladia. j. Mature flower. k. Bract and bracteoles. l. Tepals. m. Androecium with pseudostaminodia and pistillode (a–h from S. Zumaya et al. 72b; i–m from S. Zumaya et al. 72a).

2013]


441

Fig. 6. Iresine valdesii Zumaya, Flores Olv. & Borsch. at the type locality. A. Habit. B. Staminate synflorescence. C. Lower and upper leaf surface. D. Pistillate synflorescence.

442

SYSTEMATIC BOTANY

+

+

+

+

+

+

margins, glabrous to villous, acute, rounded to cleft at apex; bracteoles ovate, 1–1.8 mm long, membranous to hyaline, cleft at apex, glabrous; tepals (of mature flowers) ovate to broadly ovate (outer and middle) or ovate lanceolate (inner), 0.7–1 mm, the middle 2.3–2.8 the outer tepals 2.5–2.9 0.7–1.0 mm, the inner 2.3–2.6 0.6–0.8 mm, subcoriaceous to membranaceous at the margins, yellowish brown to dark brown at the apex, rounded to acute (middle to inner) at apex, 1-veined, the vein extending to about ¼ to 3/4 of the length of the tepal, glabrous (the outer) to woollytomentulose (the inner) in the upper abaxial half with 0.5– 1.8 mm long trichomes; filaments shortly connate (for about 10% of their length), 1.2–2.6 mm long, the pseudostaminodia linear, 0.3–0.7 mm long, papillose. Pistillate flowers with bracts shorter than bracteoles, these subequal in length to the tepals; bracts ovate, 0.8–1.4 mm long, not carinate, without veins, reddish brown to dark brown, membranous to hyaline at the margins, glabrous to villous at the apex; bracteoles broadly ovate, 1.7–2.6 mm long, membranous to hyaline, rounded to cleft at apex, glabrous; tepals (of mature flowers) ovate to ovate-lanceolate (middle and inner), the outer tepals 1.5–2.2 0.7–1 mm, the middle 1.5–2 0.7– 1 mm, the inner 1.3–2 0.5–1 mm, subcoriaceous to membranous at the margins, yellowish brown, sometimes reddish, acute to rounded at apex (outer) or acuminate (inner), (2-)3-veined, the veins extending to about 3/4 the length of the tepal or up to the apex, densely villous-woolly abaxially with 0.7–4.6 mm long trichomes, the density of trichomes increasing toward the apex; long trichomes at maturity cream, ± straight, up to twice as long as tepals. Ovary subglobose, 0.4–0.5 mm long, the style inconspicuous, the stigmas narrowly cylindrical, 0.2–0.3 mm. Seeds subspherical, 1–1.4 (–1.7) mm in diameter, orange to orange brown. Pollen spheroidal, 16–18 mm in diameter, with 16–34 apertures; pores 2.3–2.7 mm in diameter, all of equal size, the ektexinous bodies 8–12, cone-shaped with acute tips, well-separated; mesoporia broadly vaulted to almost flat, 2.4–2.9 mm wide, the tectum punctate, with perforations