Gnathia marleyi sp. nov. (Crustacea, Isopoda ...

Zootaxa 3381: 47–61 (2012) www.mapress.com / zootaxa/ Copyright © 2012 · Magnolia Press

ISSN 1175-5326 (print edition)

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ZOOTAXA ISSN 1175-5334 (online edition)

Gnathia marleyi sp. nov. (Crustacea, Isopoda, Gnathiidae) from the Eastern Caribbean CHARON FARQUHARSON1, *NICO J. SMIT2 & PAUL C. SIKKEL3 1

Centre for Aquatic Research, Department of Zoology, University of Johannesburg, P.O. Box 524, Auckland Park 2006, South Africa. Water Research Group, School of Environmental Sciences and Development, Private Bag X6001, North-West University, Potchefstroom, 2520, South Africa. E-mail: [email protected] 3 Department of Biology, Arkansas State University, P.O. Box 599, State University, AR, 72467, USA. E-mail: [email protected] Address for correspondence: N.J. Smit, School of Environmental Sciences and Development, Private Bag X6001, North-West University, Potchefstroom, 2520, South Africa. Phone: ++27 18 2292128; Fax: ++27 18 2292503; e-mail: [email protected] 2

Abstract A new species of gnathiid was collected in June-August 2008 and 2009 from various sites in the Eastern Caribbean. Third stage pranizae taken from fish hosts were maintained in fresh sea water until their moult into males or females. Distinctive features of the adult male cephalosome include a produced frontal border with conical superior fronto-lateral processes and a slightly sunken inferior conical medio-frontal process. The male mandible is 0.8 times the length of cephalosome with 10 to 11 processes on dentate blade. The adult female has a rectangular cephalosome with convex lateral margins, 1.2 times as wide as long with no paraocular ornamentation. The female frontal border is broadly rounded, produced and slightly concave anteriorly. The third stage praniza is characterised by a mandible with 8 large, triangular teeth, directed backwardly and 2 small teeth at the tip. Key words: Isopoda, Gnathiidae, Gnathia, Caribbean, morphology, free living adults, fish ectoparasitic juveniles

Introduction Gnathiid isopods are unique protelian parasites of fish with only the juvenile life stages being parasitic, feeding on fish host blood, limph or mucus, while the adults are free-living, non feeding, benthic organisms (Smit & Davies 2004). These marine isopods have a worldwide distribution and have been found from the Antarctic through to the Arctic, but mostly in warm, tropical areas where they have been reported, for example, as the most common ectoparasites of coral reef fishes on the Great Barrier Reef (GBR) (Grutter 1994). This seems to be true for the Caribbean as well as the GBR, with Kensley & Schotte (1989) listing 10 gnathiid species from the genus Gnathia, already described from various localities in the region. These 10 species are chronologically, Gnathia triospathiona Boone, 1918 (Florida, USA), Gnathia johanna Monod, 1926 (US Virgin Islands), and Gnathia virginalis Monod, 1926 (US Virgin Islands); Gnathia puertoricensis Menzies & Glynn, 1968 (Puerto Rico); Gnathia beethoveni Paul & Menzies, 1971 (Venezuela); Gnathia rathi Kensley, 1984 (Belize); Gnathia gonzalezi Müller, 1988 (Colombia); Gnathia magdalensis Müller, 1988 (Belize); and Gnathia samariensis Müller, 1988 and Gnathia velosa Müller, 1988 (both from Colombia). As taxonomy of gnathiids is based solely on the morphology of the adult male it is not surprising that only two of the above mentioned species have morphological information for the adult females and juveniles. This lack of information for juvenile (larval) gnathiids has led to researchers working on cleaning behaviour among Caribbean coral reef fishes being unable to identify parasitic juveniles to species level when collected from the fish hosts. As part of an ongoing study on the ecology of gnathiids on Caribbean coral reefs (Sikkel et al. 2006, 2009, 2011), larval specimens of these isopods were collected, kept alive and allowed to moult into adults for identification. The resultant adults did not conform to any of the 10 previously described species from the Caribbean or any other worldwide and is thus herein described as new to science.

Accepted by J. Svavarsson: 1 Jun. 2012; published: 6 Jul. 2012

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Material and methods Fish (see below) were placed in cages, at depths of 3–5 m, on shallow reefs. Gnathiids were collected from these fishes that had been placed on the reefs at dusk and retrieved just before midnight or at dawn, as described in Sikkel et al. (2009). Collections were made at six localities, from 12 species of host fishes (see material examined section below). Gnathiids collected from the fishes were reared in plastic 200 ml jars until they digested their blood meal and metamorphosed to the next developmental stage. Specimens from some of the Lameshur Bay, St. John collections that metamorphosed into adults were bred to obtain larval stages. This was done by placing males and females together in separate (one of each sex per tube) 20 ml glass tubes filled with seawater, 8–12 days after removal from the host. A piece of waterproof paper was added as a shelter. The tubes were maintained under shade at ambient temperatures and the water changed daily. Once eggs were visible in the female brood pouch, the male was removed. All newly hatched larvae and adults were preserved in 70% ETOH.

Taxonomy Family Gnathiidae Leach, 1814 Genus Gnathia Leach, 1814 Gnathia marleyi sp. nov. Figs 1–9 Material examined. Holotype. Male, 3.3 mm, 18 June 2008 off Lameshur Bay, St. John, US Virgin Islands (18°18’59.32”N, 64°43’24.5”W), American Museum of Natural History (Crustacea Cat. No. 20223). Paratypes. 10 males, 6 females, 10 third stage pranizae off Lameshur Bay, St. John, US Virgin Islands (18°18’59.32”N, 64°43’24.5”W), American Museum of Natural History (Crustacea Cat. No. 20223). Additional material. 4 males, December 2008, Saltpond Bay, St. John, USVI (18°18’35.28”N, 64°43’02.45”W), American Museum of Natural History (Crustacea Cat. No. 20223); 7 males, January 2009, Punto Soldado, Culebra, Puerto Rico (18°16’41.78’’N, 65°17’08.83”W), American Museum of Natural History (Crustacea Cat. No. 20223); 3 males, June 2009, Lee Stocking Island, Bahamas (CMRC Marine Science Laboratory boat dock) (23°77’02.66”N, 76°10’07.26”W), American Museum of Natural History (Crustacea Cat. No. 20223); 11 males, 4 third stage pranizae, August 2009, White Bay, Guana Island, British Virgin Islands (18°28”28.31”N, 64°34’30.83”W), American Museum of Natural History (Crustacea Cat. No. 20223); 4 males, October 2009, Fort Bay Harbor, Saba, Netherlands Antilles (17°36.907N, 63°14.938W); 24 males, May–August 2010–2011, Lameshur Bay, St. John, US Virgin Islands (18°18’59.32”N, 64°43’24.5”W), American Museum of Natural History (Crustacea Cat. No. 20223). Hosts. French grunt, Haemulon flaviolineatum (Desmarest, 1823); Bluestripe grunt, H. sciurus (Shaw, 1803); White grunt, H. plumieri (Lacepede, 1801); Schoolmaster snapper, Lutjanus apodus (Walbaum, 1792); Mangrove snapper, L. griseus (Linnaeus, 1758); Red hind, Epinephelus guttatus (Linnaeus, 1758); Longspine squirrelfish, Holocentrus rufus (Walbaum, 1792), Longfin damselfish, Stegastes diencaeus (Jordan and Rutter, 1897); Threespot damselfish, Stegastes planifrons (Cuvier, 1830); Ocean surgeon, Acanthurus bahianus Castelnau, 1855; Foureye butterflyfish Chaetodon capistratus Linnaeus, 1758; Princess parrotfish, Scarus taeniopterus Desmarest, 1831; Redband parrotfish Sparisoma aurofrenatum (Valenciennes, 1840). Diagnosis. Eyes large, 0.28 times length of cephalosome. Frontal border produced with conical superior fronto-lateral processes and an inferior conical medio-frontal process which is slightly sunken. Mandible 0.8 times length of cephalosome with 10 to 11 processes on dentate blade. Appendix masculina absent. Male description (Figs 1A–F, 2A–C, 3A–E) Description. Size: Total length of holotype: 3.3 mm. Total length of paratypes: 2.6–3.7 mm (3.0±0.6 mm, n=10). Cephalosome (Fig. 1A, B) rectangular, 1.4 times as wide as long, dorsal sulcus shallow, half length of cephalosome, lateral margins slightly convex, central area slightly concave, posterior margin convex, with central area concave. Eye slightly less than one-third of cephalosome (Fig. 1B). Many granules distributed dorsally and

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FARQUHARSON ET AL.

FIGURE 1. Gnathia marleyi sp. nov. Male holotype, 3.3 mm (Crustacea Cat. No. 20223). A, Full length dorsal view. B, Frontal border and mandibles. C, Antenna 1. D, Antenna 2. E, Mandible. F, Left pleopod 2. G, Pleotelson and uropods. Scale-bars: A, 1 mm; B, 500 μm; C–G, 200 μm.

GNATHIA MARLEYI SP. NOV. FROM THE CARIBBEAN

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FIGURE 2. Cephalosome appendages of male Gnathia marleyi sp. nov. Male holotype, 3.3 mm (Crustacea Cat. No. 20223). A, Pylopod. B, Maxilliped. C, Articles 2 and 3 of pylopod. Scale-bars: A, B, 200 μm; C, 100µm.


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FIGURE 3. Pereopods 2 to 6 (A–E) of male Gnathia marleyi sp. nov. Male holotype, 3.3 mm (Crustacea Cat. No. 20223). Scale-bar: 200 μm.



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laterally around eyes, as well as on the dorsal surface of cephalosome. Longer plumose setae concentrated around the dorsal surface around eyes. Median tubercle prominent with granules distributed randomly on dorsal surface (Fig. 1B). Frontal border (Fig. 1B) slightly produced. Superior fronto-lateral processes conical, with 3 to 4 long, simple setae on each process, inferior medio-frontal process conical with concave central area. Pereon (Fig. 1A) with numerous cuticular extensions, few long simple setae and pectinate scales on anterior, lateral and posterior margins of all pereonites. Pereonites 2 and 3 of similar size, widest part of the body, almost as wide as pereonite 5, lateral margins pointing anteriorly. Pereonite 4 with prominent anterior constriction. Pereonites 5 and 6 not fused, both at least twice as long as other pereonites. Pereonite 6 posterior margin concave, with lobi laterales, no lobuii. Pereonite 7 small, dorsally visible with rounded posterior margin, overlapping first pleonite. Antenna 1 (Fig. 1C) first article of peduncle with 2 plumose setae distally, second article with 1 plumose seta and 4 to 5 simple setae distally, third article with 8 to 9 simple setae distally, all three articles randomly covered with pectinate scales. Flagellum with 5 articles, about 0.96 times as long as article 3 of peduncle, first article with 3 simple setae distally; article 3 with 1 long aesthetasc seta and 1 simple seta, article 4 with one aesthetasc seta, article 5 terminating in one aesthetasc and three simple setae. Antenna 2 (Fig. 1D) about 1.5 times longer than antenna 1, peduncle article 1 with single plumose seta distally; article 3 with single proximal seta, single plumose seta and 7 to 8 long simple setae distally, article 4 with 8 to 9 simple setae along lateral margins, 4 distal plumose setae and 8 to 9 simple setae distally, all 4 articles randomly covered with simple setae and pectinate scales, flagellum with 7 articles, flagellum about 1.4 times as long as peduncle article 4. Mandible (Fig. 1A, B, E) 1.6 times as long as wide, more than two-thirds length of the cephalosome, narrow basal neck, curved inwards with 10–11 strong denticulations on the dentate blade, single seta between each process. Strong incisor present, single long simple mandibular seta extending out of the carina. Pectinate scales randomly on dorsal surface of dentate blade. Maxilliped (Fig. 2A) proximal article largest with single lateral endite just reaching article 3. Outer margin of proximal article with cuticular extensions. Distal 4 articles bearing plumose setae on lateral margins in order of 66-5-7, mesial borders with short, simple setae. Palp 2.8 times as long as wide. Coupling hooks absent. Pylopod (Fig. 2B) convex mesial border fringed with 29–30 long, plumose setae, short, simple lateral and proximal setae; 5 long simple setae distally on posterior surface. Article 1 with 3 areolas increasing in size proximally. Article 2 oval, 1.2 times as long as wide, margins setose, 4 long simple setae distally on posterior surface and single setae mid-laterally. Article 3 minute, with fringing simple setae. Pleon and pleotelson less than third of total body length, epimera dorsally visible on all pleonites. Numerous simple setae and pectinate scales on lateral and dorsal surface of all pleonites. Pleotelson (Fig. 1G) wider than long, lateral margins slightly convex with central margins concave, dorsal surface with two pairs of simple setae, many pectinate scales on dorsal surface, distal apex terminating in pair of simple setae. Pereopods (Fig. 3A–E) 2–6 similar in shape. Numerous long setae on basis of all pereopods; pereopod 3 basis with 2 plumose setae anteriorly; pereopods 5 and 6 basis with 1 and 2 posterior plumose setae respectively (Fig. 3B). Carpus of pereopod 2 with single serrate seta posteriorly and pereopod 6 carpus with single serrate setae anteriorly. Propodus of pereopod 3 with single plumose seta distally. All pereopods with pectinate scales randomly distributed over surface. Pleopod 2 (Fig. 1F) endopod longer and wider than exopod, endopod with 8 plumose setae and exopod with 9 plumose setae, lateral margins of endopod and exopod covered with short simple setae. Sympodite with 2 retinaculae on medial margin and single simple seta on opposite margin, surface covered with pectinate scales. Appendix masculina absent. Pleopods 1, 3–5 similar to pleopod 2. Uropodal (Fig. 1G) endopod extending beyond apex of pleotelson, exopod reaching apex. Endopod longer and wider than exopod, with 7 long plumose setae, exopod with 5 to 6 plumose setae; pectinate scales on lateral margins of endopod and exopod. Uropodal basis with single simple seta and covered with pectinate scales. Adult female description (Figs 4A–F, 5A–B, 6A–E) Description. Size: Total length of paratypes: 2.1–3.1 mm (2.6±0.5 mm, n=8). Cephalosome (Fig. 4A, B) rectangular, short and broadened, 1.2 times as wide as long. Eyes almost half the length of cephalosome. Frontal border (Fig. 4B) broadly rounded, produced, slightly concave anteriorly. Pereon (Fig. 4A) swollen, covered with numerous long simple setae and cuticular extensions on lateral and dorsal surface,


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FIGURE 4. Gnathia marleyi sp. nov. Female paratype (Crustacea Cat. No. 20223). A, Full length dorsal view. B, Dorsal cephalosome. C, Antenna 1. D, Antenna 2. E, Left pleopod 1. F, Pleotelson and uropods. Scale-bars: A, 1 mm; B, F, 200 μm; C, D, E, 100 μm.



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FIGURE 5. Gnathia marleyi sp. nov. Female paratype (Crustacea Cat. No. 20223). A, Maxilliped. B, Pylopod. Scale-bars: A, B, 200 μm.

sutures between pereonite 5-7. Pereonites 4 and 5 with areae laterales at leg attachment. Pereonite 6 with lobi laterales. Pereonite 7 dorsally visible, small with rounded posterior margin, overlapping first pleonite. Most setae on lateral and anterior margins of pereonites. Antenna 1 (Fig. 4C) few short, simple setae on distal end of article 1 and 2, peduncle article 2 with single plumose seta distally; 8 to 9 simple setae distally on third peduncle article. Flagellum 1.4 times as long as article 3 of peduncle, aesthetasc setae similar to those of male, article 4 terminating in 2 to 3 long, simple setae. Antenna 2 (Fig. 4D) peduncle article 1 and 2 with few simple setae on the distal end, article 3 and 4 with 5 to 7 setae distally. Peduncle articles of both antennae covered with pectinate scales. Maxilliped (Fig. 5A) base and palp of 5 articles. Endite not reaching article 2 of palp. Palp bearing plumose setae on lateral margins in order of 4-4-3-5-7. Article 5 of palp with 4 simple setae distally. Coxa with attached oostegite broader and slightly longer than the palp. Mesial borders of basis, oostegite and the palp densely setose. Pylopod (Fig. 5B) article 1 broad, robust, curved anteriorly, with a simple seta mid-ventrally, article 2 with 4 simple setae distally and article 3 with 4 to 5 long simple setae distally. Oval-shaped oostegite, 1.7 times as long as wide, covers mouthparts ventrally, not surpassing frontal border. Posterior surface of all articles covered with cuticular extensions. Pleon (Fig. 4A) and pleotelson more than a third of the total length. Epimera not distinct. Long simple setae at lateral margin and centre of each pleonite and pectinate scales randomly distributed on lateral and dorsal surface of all pleonites.


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FIGURE 6. Pereopods 2 to 6 (A–E) of a female Gnathia marleyi sp. nov. Female paratype (Crustacea Cat. No. 20223). Scale-bar: 200 μm.



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Pleotelson (Fig. 4F) wider than long, lateral margins slightly concave with central area convex, dorsal surface with 1 pair of simple setae and many short simple setae and pectinate scales on dorsal surface, distal apex with 2 long, simple setae. Pereopods (Fig. 6A–E) 2–6 similar in shape. Similar to that of male. Dorsal and ventral surface of all pereopods randomly covered with pectinate scales. Pleopod (Fig. 4E) endopod and exopod both fringed distally with 8 to 9 plumose setae. Retinacula present on sympodite, with single simple seta on the opposite lateral margin. Pleopods similar. Uropodal (Fig. 4F) endopod stretching beyond apex of pleotelson, exopod reaching apex. Endopod longer and wider than exopod, both fringed with 7 long plumose setae and covered with pectinate scales. Uropodal basis with single simple seta and covered with pectinate scales. Third stage praniza (P3) (Figs 7A–F, 8A–E, 9A–E) Description. Size: Total length of paratypes: 2.3–3.6 mm (3.2±0.6 mm, n=10). Cephalosome (Fig. 7A) 1.5 times wider than long, posterior margin slightly concave, slightly wider than anterior margin, lateral margins slightly convex. Large, well-developed, oval-shaped, bulbous, compound eyes on lateral margins of cephalosome, almost same length as cephalosome. Medio-anterior margin of cephalosome slightly concave with lateral concave excavations to accommodate first articles of antennae. Tubercles and setae on dorsal surface absent. Labrum (Fig. 7A) prominent, half as long as cephalosome, semicircular with apical process, anterior margin concave and truncated posterior margin. Ventral parts of labrum gutter-like with central groove, covers mandibles dorsally and laterally. Pereon (Fig. 7A) wider than cephalosome, 1.8 times as long as wide. Pereonite 2 and 3 similar in size and shape. Pereonite 4 twice as wide as long, lateral sides tapering towards rounded posterior margin, posterior margin stretching over pereonite 5, lateral shields at leg attachment. Pereonite 5 consists of elastic membrane fully expanded in praniza stage with blood meal, bulbous shields present on lateral sides at leg attachment. Pereonite 6 rectangular, with posterior margin slightly concave, lateral shields at leg attachment. Pereonite 7 dorsally visible, small with rounded posterior margin, overlapping first pleonite. No setae present on pereonites. Antenna 1 (Fig. 7C) peduncle article 1 with 2 simple setae, article 2 with 5 simple setae distally and article 3 with 3 simple setae distally and single seta mid-laterally. Flagellum with four articles, about 1.5 times as long as peduncle article 3. Article 1 with single seta distally, few setae on article 2 and 3, article 2 with single aesthetasc seta distally, article 4 terminating in single aesthetasc seta and 3 simple setae. Antenna 2 (Fig. 7D) peduncle article 1 and 2 with few simple setae, article 3 with single plumose seta and 4 to 5 simple setae distally; article 4 with 5 to 6 distal setae and 2 plumose setae. Flagellum article 7 terminating with 4 simple setae. Mandible (Fig. 8A) stout, swollen at base, distal margin styliform with 8 large, triangular teeth, directed backwardly and 2 small teeth at tip. Paragnath (Fig. 8E) elongated, gutter-like, terminates in sharp point. Maxillule (Fig. 8D) long, slender, swollen at the base, 7–8 small teeth on distal inner margin. Maxillae not visible. Maxilliped (Fig. 8C) palp with 3 articles, first article with 6 to 7 small teeth, second article with 5 to 6 simple setae and article 3 terminating in sharp point, with simple seta mid-laterally. Gnathopod (Fig. 8B) smaller than pereopods, 7 articles, few simple setae on all articles, 1 tooth-shaped tubercle dustally on third article and a serrate seta distally on the fourth article. Dactylus strongly hooked. Pleon (Fig. 7A) and pleotelson about a quarter of the total length, few simple setae on lateral sides of pleonites, few pectinate scales distributed mid-dorsally on each pleonite. Pleotelson (Fig. 7F) triangular, longer than wide, anterior and posterior part of lateral margin slightly concave, mid-anterior parts slightly convex. Pair of simple setae on posterior dorsal surface, distal apex terminating in 2 simple setae. Pereopods (Fig. 9A–E) similar in shape to male pereopods, but differing in setation and numbers of tubercles. Pleopod 2 (Fig. 7E) endopod larger than exopod, both fringed distally with 9 long plumose setae, cuticular extensions on all margins. Sympodite with retinacula and single simple seta on the opposite lateral margin. Pleopods 1, 3 to 5 similar to pleopod 2. Uropodal (Fig. 7F) endopod extending to approximately same length as apex of pleotelson, exopod not reaching apex. Endopod longer and wider than exopod, both fringed with long, simple setae. Endopod with 7 mesial plumose setae and exopod with 6 plumose setae. Few pectinate scales on lateral dorsal areas of endopod and exopod. Uropodal basis with one simple seta and anterior-dorsal surface covered with few pectinate scales.


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FIGURE 7. Gnathia marleyi sp. nov. Praniza 3 paratype (Crustacea Cat. No. 20223). A, Full length dorsal view. B, Dorsal cephalosome with labrum. C, Antenna 1. D, Antenna 2. E, Left pleopod 2. F, Pleotelson and uropods. Scale-bars: A, 1 mm; B–F, 200 µm; C–E, 100 µm.



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FIGURE 8. Gnathia marleyi sp. nov. Praniza 3 paratype (Crustacea Cat. No. 20223). A, Mandible. B, Maxilliped. C, Gnathopod. D, Maxillule. E, Paragnath. Scale-bars: A–E, 100 µm.


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FIGURE 9. Gnathia marleyi sp. nov. Praniza 3 paratype (Crustacea Cat. No. 20223). Pereopods 2 to 6 (A–E). Scale-bar: 200 μm.



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Etymology. The species is named for the famous Caribbean singer, Bob Marley, as this species is as uniquely Caribbean as Bob Marley.

Remarks Gnathia marleyi sp. nov. males are larger than G. velosa (1.5 mm), smaller than G. triospathiona (8.8 mm) and similar in size to the other 8 known Caribbean Gnathia species (Boone 1918; Müller 1988; Kensley & Schotte 1989). Gnathia gonzalezi and G. samariensis both differ from G. marleyi sp. nov. in having shorter and broader bodies, instead of the longer and narrower form of G. marleyi sp. nov., and the constriction between the 3rd and 4th pereonite is not as pronounced in these two species as in G. marleyi sp. nov. (Müller 1988). The male of G. beethoveni has a mediofrontal process which is deeply excavated to produce 2 separate processes which are produced (Paul & Menzies 1971), whereas G. marleyi sp. nov. has a mediofrontal process which is apically notched and sunken to a non-produced position. In G. gonzalezi there is no distinction between medial and lateral processes; the frontal border is slightly produced with the central area being deeply sunken (Müller 1988). In contrast, G. magdalenensis’s mediofrontal process has 2–4 short setae, the lateral processes have slightly serrate outer margins and two setae dorsally (Müller 1988), but G. marleyi sp. nov. has a single seta on each dorsal surface of the lateral processes and 2–3 setae extending from their ventral surface. The mediofrontal process of G. virginalis is apically blunt, the lateral processes each have two setae dorsally and three setae projecting from the ventral surface (Monod 1926). Gnathia johanna’s mediofrontal process is bigger and wider than that of G. marleyi sp. nov. with the central area terminating in a tiny tip, and the mediofrontal process is produced. Gnathia rathi has 2 lateral processes and a straight central area with no medial process that has 4 setae arranged in pairs of 2 (Kensley 1984). The frontal border of G. puertoricensis is the most similar to that of G. marleyi sp. nov. in having conical superior fronto-lateral processes and an inferior conical medio-frontal process, but differ in that G. marleyi’s sp. nov. medio-frontal process has a distinct notch and no setae, whereas that of G. puertoricensis ends blunt with two stout setae (Menzies & Glynn 1968). Gnathia marleyi sp. nov. can further be separated from G. puertoricensis in cepholone shape, presence of many long plumose setae covering the cephalosome and pereon, and number of setae on the lateral margins of the maxilipedal palp. Distinct differences also exist in the mandible morphology of the Caribbean species with those of G. beethoveni each having two pairs of setae at the inner dorsal margin (Paul & Menzies 1971), whereas G. marleyi sp. nov. has only a single seta on each mandible. The mandibular blade of G. virginalis is rounded and that of G. marleyi sp. nov. is rectangular. Gnathia gonzalezi and G. puertoricensis mandibles are shorter and broader than those of G. marleyi sp. nov. Gnathia magdalenensis has a distinct inner lobe present on the mandible, while the mandible of G. vellosa has a pointed apex and carina that is distinctly notched. The mandibles of G. yucatanensis are robust, sickle-shaped in dorsal view, the dorsal carina is produced anteriorly as a strong tooth, and the ventral margin has a strong, rounded tooth projecting anterioventrally. Female and larval descriptions of the two gnathiid species mentioned in the introduction, were not very detailed, and thus are unable to contribute any significant facts to compare or remark upon. The above description is thus the first detailed description of the females and juveniles of any of the known gnathiid species from the Caribbean and no comparisons to other species are at this stage possible.

Conclusion This paper reported on a single new gnathiid species and all of its life stages collected from the eastern Caribbean. The male, female and third stage praniza of this new species were all described in detail. The descriptions of the female and larva, which are not often described in such detail, should enable parasitologists to identify them more readily when they are collected without the adult males. Such detailed larval description, together with several other recent larval descriptions, will serve to enhance the information available on this particular life stage. This is important since, as noted previously, gnathiid larvae are frequently observed and collected in high numbers from various fish hosts in coral reef locations. Constructing a taxonomic key to help scientists identify gnathiid larvae more easily is therefore an important target to aim for. Finally, another benefit is that detailed description of the larval stage offers help in making sense of the vast data collected on diel patterns of gnathiid emergence, and cleaning behaviour among fishes, in the Caribbean.


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Acknowledgments We thank the staff at the Virgin Islands Environmental Resource Station (VIERS) and the Center for Marine and Environmental Studies (US Virgin Islands), Guana Island (British Virgin Islands), the Saba Island Marine Park and Sea and Learn program (Saba Island, Netherlands Antilles), Lee Stocking Island Marine Laboratory (Bahamas) CORALations and Escuela Ecologica (Culebra, Puerto Rico) for logistic support and use of their facilities. For assisting with collection and processing of parasites, we thank: D. Nemeth, A. McCammon, J. Artim, W. Jenkins, A. Coile, R. Welicky and volunteers from the 2008 and 2009 Virgin Islands Earthwatch teams (US and British Virgin Islands); K. Wolfe, G. van Laake, B. Janssens, and C. Davies (Saba); M. Hixon, M. Albins, T. Kiddinger, E. Pickering, G. Scheer, and K. Obrien (Bahamas); and M. Lucking and students from Escuela Ecologica and the Centre College Caribbean Natural History class (Culebra). We are especially grateful to W. Sears for help with rearing multiple stages of gnathiids. This work was generously funded by Earthwatch Institute, the Durfee Foundation, the Falconwood Corporation, Microsoft Corporation, Sea and Learn Saba, and National Science Foundation grant 08-51162 (Hixon). This is publication number 82 from the Center for Marine and Environmental Science at the University of the Virgin Islands. We are also grateful to Prof Angela Davies-Russell, Kingston University, UK, for proofreading earlier drafts of this paper. The financial assistance of the South African National Research Foundation (NRF project IFR2011040100022) towards this research is also acknowledged. Opinions expressed and conclusions arrived at, are those of the authors and are not necessarily to be attributed to the NRF.

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