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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.
Accepted by J. Svavarsson: 1 Jun. 2012; published: 6 Jul. 2012
ZOOTAXA
ISSN 1175-5326 (print edition)
ISSN
1175-5334 (online edition)
Copyright © 2012 · Magnolia Press
Zootaxa 3381: 4761 (2012)
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Article
47
Gnathia marleyi sp. nov. (Crustacea, Isopoda, Gnathiidae) from the Eastern
Caribbean
CHARON FARQUHARSON
1
, *NICO J. SMIT
2
& PAUL C. SIKKEL
3
1
Centre for Aquatic Research, Department of Zoology, University of Johannesburg, P.O. Box 524, Auckland Park 2006, South Africa.
2
Water Research Group, School of Environmental Sciences and Development, Private Bag X6001, North-West University, Potchefst-
room, 2520, South Africa. E-mail: nico.smit@nwu.ac.za
3
Department of Biology, Arkansas State University, P.O. Box 599, State University, AR, 72467, USA. E-mail: psikkel@astate.edu
Address for correspondence: N.J. Smit, School of Environmental Sciences and Development, Private Bag X6001, North-West Univer-
sity, Potchefstroom, 2520, South Africa. Phone: ++27 18 2292128; Fax: ++27 18 2292503; e-mail: nico.smit@nwu.ac.za
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.
FARQUHARSON ET AL.
48 · Zootaxa 3381 © 2012 Magnolia Press
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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GNATHIA MARLEYI SP. NOV. FROM THE CARIBBEAN
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 m; C–G, 200 m.
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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 m; C, 100µm.
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GNATHIA MARLEYI SP. NOV. FROM THE CARIBBEAN
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 m.
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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 6-
6-5-7, 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: 2.13.1 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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GNATHIA MARLEYI SP. NOV. FROM THE CARIBBEAN
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 m; C, D, E,
100 m.
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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
m.
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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GNATHIA MARLEYI SP. NOV. FROM THE CARIBBEAN
FIGURE 6. Pereopods 2 to 6 (A–E) of a female Gnathia marleyi sp. nov. Female paratype (Crustacea Cat. No. 20223). Scale-bar: 200
m.
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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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GNATHIA MARLEYI SP. NOV. FROM THE CARIBBEAN
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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GNATHIA MARLEYI SP. NOV. FROM THE CARIBBEAN
FIGURE 9. Gnathia marleyi sp. nov. Praniza 3 paratype (Crustacea Cat. No. 20223). Pereopods 2 to 6 (A–E). Scale-bar: 200 m.
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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 3
rd
and 4
th
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.
magdalenensiss 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 johannas 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. marleyis 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.
Zootaxa 3381 © 2012 Magnolia Press · 61
GNATHIA MARLEYI SP. NOV. FROM THE CARIBBEAN
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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... In 1993, Müller (1993) proposed Gnathia puertoricensis Menzies & Glynn, 1968 as a junior synonym for G. virginalis Monod, 1926 based on the variation in the characters that separated these two species (granulation and tubercles on the anterior pereonites and cephalon). Although not recognised in subsequent publications on gnathiids from this region (George 2003;Farquharson et al. 2012), this synonymisation appears to still be valid and the information regarding both species is combined in Table 1. ...
... Recently, there has been a growing interest in gnathiids from this region specifically regarding their role in cleaner interactions (Artim et al. 2017), food web ecology (Demopoulos and Sikkel 2015), and their role as potential vectors of blood parasites (Cook et al. 2015). However, all of this work has focused on a single species, G. marleyi Farquharson, Smit & Sikkel, 2012, and therefore it is also the only species from this region with known hosts for the parasitic larval stage. These host fishes include Acanthurus bahianus Castelnau, 1855; Chaetodon capistratus Linnaeus, 1758; Epinephelus guttatus (Linnaeus, 1758); Haemulon flaviolineatum (Desmarest, 1823); H. plumieri (Lacepede, 1801); H. sciurus (Shaw, 1803); Holocentrus rufus (Walbaum, 1792); Lutjanus apodus (Walbaum, 1792); L. griseus (Linnaeus, 1758); Scarus taeniopterus Desmarest, 1831;Sparisoma aurofrenatum (Valenciennes, 1840); Stegastes diencaeus (Jordan & Rutter, 1897); and S. planifrons (Cuvier, 1830) (see Farquharson et al. 2012). ...
... However, all of this work has focused on a single species, G. marleyi Farquharson, Smit & Sikkel, 2012, and therefore it is also the only species from this region with known hosts for the parasitic larval stage. These host fishes include Acanthurus bahianus Castelnau, 1855; Chaetodon capistratus Linnaeus, 1758; Epinephelus guttatus (Linnaeus, 1758); Haemulon flaviolineatum (Desmarest, 1823); H. plumieri (Lacepede, 1801); H. sciurus (Shaw, 1803); Holocentrus rufus (Walbaum, 1792); Lutjanus apodus (Walbaum, 1792); L. griseus (Linnaeus, 1758); Scarus taeniopterus Desmarest, 1831;Sparisoma aurofrenatum (Valenciennes, 1840); Stegastes diencaeus (Jordan & Rutter, 1897); and S. planifrons (Cuvier, 1830) (see Farquharson et al. 2012). ...
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Gnathia bermudensissp. nov. is described from mesophotic coral ecosystems in Bermuda; it is distinguished by pronounced and pointed supraocular lobes, two superior frontolateral processes and a weak bifid mediofrontal process, pereonite 1 not fused dorsally with the cephalosome, and large eyes. This is the first record of a species of Gnathia from Bermuda. A synopsis and key to the other Gnathia species from the Greater Caribbean biogeographic region is provided.
... Wild juveniles, as opposed to reared first stages, can be used to seed a culture where only one gnathiid species is expected in the wild. This is the case for G. marleyi, which is the only known species in this part of the Caribbean region (Sikkel et al., 2009(Sikkel et al., , 2011Farquharson et al., 2012b). ...
... Males that had fed on their preferred hosts also moulted into adults more quickly (Nagel and Grutter, 2007). Gnathia marleyi can successfully infest nine fish families and two invertebrates (sea slug, Elysia crispate; fireworm, Hermodice carunculata) in the wild or laboratory setting (Farquharson et al., 2012b;Coile and Sikkel, 2013;Nicholson et al., 2019). In the wild, gnathiid loads increase with host size, across species, as well as within species, including the species H. melapterus (Grutter and Poulin, 1998). ...
... It would also increase the breadth and relevance of experiments using gnathiids. However, the general body plan of juvenile gnathiids and relative gut volumes, and thus host blood volume likely removed, is extremely similar across multiple species (Ferreira et al., 2009;Farquharson et al., 2012b;Ota et al., 2012). This implies the effect of blood removal alone on the host is not likely to differ hugely across species. ...
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The reliance of parasites on their hosts makes host-parasite interactions ideal models for exploring ecological and evolutionary processes. By providing a consistent supply of parasites, in vivo monocultures offer the opportunity to conduct experiments on a scale that is generally not otherwise possible. Gnathiid isopods are common ectoparasites of marine fish, and are becoming an increasing focus of research attention due to their experimental amenability and ecological importance as ubiquitous harmful blood-feeding “mosquito-like” organisms. They feed on hosts once during each of their three juvenile stages, and after each feeding event they return to the benthos to digest and moult to the next stage. Adults do not feed and remain in the benthos, where they reproduce and give birth. Here, we provide methods of culturing gnathiids, and highlight ways in which gnathiids can be used to examine parasite-host-environment interactions. Captive-raised gnathiid juveniles are increasingly being used in parasitological research; however, the methodology for establishing gnathiid monocultures is still not widely known. Information to obtain in vivo monocultures on teleost fish is detailed for a Great Barrier Reef, (Australia) and a Caribbean Sea (US Virgin Islands) gnathiid species, and gnathiid information gained over two decades of successfully maintaining continuous cultures is summarised. Providing a suitable benthic habitat for the predominantly benthic free-living stage of this parasite is paramount. Maintenance comprises provision of adequate benthic shelter, managing parasite populations, and sustaining host health. For the first time, we also measured gnathiids’ apparent attack speed (maximum 24.5 cm sec⁻¹; 6.9, 4.9/17.0, median, 25th/75th quantiles) and illustrate how to collect such fast moving ectoparasites in captivity for experiments. In addition to providing details pertaining to culture maintenance, we review research using gnathiid cultures that have enabled detailed scientific understanding of host and parasite biology, behaviour and ecology on coral reefs.
... Among Gnathia species around the world, G. capitellum sp. nov. is most similar to G. marleyi Farquharson, Smit, and Sikkel, 2012. Gnathia marleyi is easily distinguished from G. capitellum sp. ...
... nov. by compound eyes occupying almost same length as head, triangular pleotelson with a slightly concave lateral margin, and uropodal endopod extending to approximately same length as apex of pleotelson (Farquharson et al. 2012). In contrast, eyes occupy ca. ...
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Adult male and larva of Gnathia capitellum sp. nov. (Crustacea: Isopoda: Gnathiidae) are described. The specimens were laboratory-reared larvae that infested host fishes collected by longline fishing in a coastal bay of Izu Peninsula and adult males found in dredge samples from shallow water (depth: 11–12 m) of Miura Peninsula, central Japan. Adult males of G. capitellum sp. nov. were easily distinguished from the other species of Gnathia Leach, 1814 from around the world by the small oval head and the inner margin of pylopod without plumose setae. Most other Gnathia species have a large rectangular head and plumose setae present on the article 1 of pylopod. Appearance of the adult male resembles the genus Afrignathia Hadfield and Smit, 2008 rather than Gnathia but Afrignathia has maxilla 1 which is absent in all known male gnathiids in the world including G. capitellum sp. nov. Fish parasitic larva of G. capitellum sp. nov. is also described herein. This larva closely resembles larvae of the genus Gnathia, but can be distinguished from the other Gnathia species by the remarkably oval-shaped basis in pereopods 2–4.
... Gnathiids also tend to have broad host ranges covering multiple fish feeding guilds. For example, Gnathia marleyi in the eastern Caribbean feeds on at least 42 host species from 17 families (Farquharson et al. 2012, Coile and Sikkel 2013, Hendrick et al. 2019G. Hendrick, unpublished data). ...
... In the Pacific, there is a much greater diversity of coral species (Veron et al. 2015: Fig. 4). There also appears to be much greater diversity of gnathiids in the tropical Indo-Pacific (Svavarsson and Bruce 2012, Svavarsson and Bruce 2019) compared with the Caribbean (Farquharson et al. 2012). This interplay of selection forces on diverse Pacific coral reefs deserves future study including the effect of gnathiidspecies specialization and diversity on the overall transport of energy and nutrients by the ectoparasite functional group among fish species comprising Brandl et al.'s eight core processes (Brandl et al. 2019). ...
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Ecosystem degradation due to anthropogenic activities is the primary issue of our times. Theoretical analyses as well as efforts to restore and manage ecosystems depend on comprehensive metrics of ecosystem function. In the case of complex ecosystems such as tropical coral reefs-especially where monitoring , management, and restoration are important-multiple metrics reflecting key functional groups are required to accurately reflect ecosystem function and when necessary, diagnose degree and kind of ecosystem degradation. We propose inclusion of the generalist ectoparasite functional group as a measure of ecosystem function of coral reefs. This functional group is adaptable to loss of other community members and may experience an increase in abundance as ecosystem function declines. Fish-parasitic gnathiid isopods are a member of this group, resident though inconspicuous in coral-reef communities. On Caribbean coral reefs, based on 938 light-trap samples, we observed a negative correlation between abundance of smaller-sized gnathiids and abundance of live coral, a natural predator of gnathiids. Plots grouped by coral cover-a measure of success of the ecosystem engineer-and ectoparasite abundance varied significantly in community composition including abundance of macroalgae, turf algae, and farming Stegastes spp. damselfish reflecting shifts in community structure. Changes in gnathiid abundance with respect to the abundance of organisms participating in each of the core functional processes driving coral-reef ecosystems reflect broad connectivity of gnathiid parasites across the ecosystem. We conclude that the hyperabundance of a small, cryptic, generalist parasite, when used in combination with a metric of abundance of the primary ecosystem engineer, can provide one nuanced measure of the ecosystem vulnerability to collapse.
... Gnathia marleyi (Farquharson et al. 2012) is a common parasitic gnathiid isopod on shallow reefs in the northeastern Caribbean Sea. G. marleyi is primarily active at night and during crepuscular hours (Sikkel et al. 2006(Sikkel et al. , 2009. ...
... G. marleyi is primarily active at night and during crepuscular hours (Sikkel et al. 2006(Sikkel et al. , 2009. It is a generalist parasite (Sikkel and Welicky 2019) that infests over 40 different species of fish (Farquharson et al. 2012;Coile and Sikkel 2013;Sikkel et al. 2014;Jenkins et al. 2018;Hendrick et al. 2019). However, some host species are more susceptible to infestation by G. marleyi than others. ...
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Gnathiid isopods are common crustacean parasites that inhabit all oceans from shorelines to depths of over 3000 m and use chemical cues to find their marine fish hosts. While gnathiids are host-generalists, hosts vary in their susceptibility to infestation. However, the mechanisms that mediate differential susceptibility are unknown. Here we used a combination of field and laboratory experiments to investigate if the chemical attractiveness of hosts explains differences in susceptibility of Caribbean reef fishes to infestation by a common Caribbean gnathiid isopod, Gnathia marleyi. We showed that while G. marleyi can detect and locate hosts using only chemical cues, they do not exhibit a preference for chemical cues produced by more susceptible fish species. We conclude that species-specific chemical cues are not the main mechanism driving differences in host susceptibility to gnathiid isopod infestation and that visual or post-attachment factors such as ease of obtaining a blood meal are likely mediators.
... Gnathiid isopods (Gnathia marleyi; Farquharson et al., 2012) were collected from May 2015 to August 2017 in Brewer's Bay, St. Thomas (18820 0 37 00 N, 064858 0 38 00 W), Lameshure Bay, St. John (18819 0 08 00 N, 064843 0 36 00 W), White Bay, Guana Island (18828 0 30 00 N, 64834 0 15 00 W), Tamarindo Beach, Isla Culebra (18817 0 13 00 N, 65817 0 04 00 W), and Cayo Enrique, Puerto Rico (17857 0 11.9 00 N, 6782 0 47.7 00 W) using benthic light traps (see Artim and Sikkel, 2016 for design) as part of a broader study on factors influencing the abundance and distribution of gnathiids on shallow Caribbean reefs. Light traps were placed on the reef prior to sunset and were retrieved just after sunrise the next morning. ...
... Thus, our observations do not appear to reflect species differences in host preference. Gnathia marleyi has been confirmed to feed on at least 37 fish species (Farquharson et al., 2012;Coile and Sikkel, 2013; G. C. Hendrick and colleagues, unpubl. data) and, even though individual light traps yielded hundreds of gnathiids and soft-bodied invertebrates, most unfed gnathiids were not attached to invertebrates. ...
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... to popular culture icons, such as musicians (e.g., Bob Marley, Gnathia marleyi; Farquharson et al. 2012b), politicians (e.g., President Obama, Baracktrema obamai; Roberts et al. 2016), and television characters (e.g., Xena, Warrior Princess, Elthusa xena; van der Wal et al. 2019). There is room for creativity and exploration in parasitology, as many currently undescribed species still await discovery. ...
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A parasite is an organism that lives in an intimate and durable relationship with its host and imposes a cost on that host, in terms of its ability to survive, grow, and/or reproduce. Despite the fact that more than 40% of animal species are parasites, parasitism is rarely discussed in introductory biology courses. This may be because parasites are often hidden within their hosts—and therefore easy to ignore. But parasites have important roles to play in ecosystems and we ignore them at our own peril. In this module, students have the opportunity to discover the hidden world of parasites: they will come face to face with living parasites, learn about what differentiates parasites from free-living species, observe some common adaptations to a parasitic lifestyle, explore the ecological role of parasites in food webs, and assess how parasite abundance might change in a changing world. To accomplish these goals, this module includes an introductory PowerPoint presentation (including a video of parasite ecologist Dr. Chelsea L. Wood delivering this introductory lecture) and two exercises. The first exercise is a wet lab that involves dissecting an easy (and disturbing) source of live parasite material: fresh fish from your local seafood market. The second exercise is a computer lab that will allow students to engage with real data to answer the question: how do human impacts on ecosystems change the abundance of parasites in wildlife? This module will introduce students to the basics of parasite ecology and provide an opportunity to practice their data analysis and interpretation skills.
... to popular culture icons, such as musicians (e.g., Bob Marley, Gnathia marleyi; Farquharson et al. 2012b), politicians (e.g., President Obama, Baracktrema obamai; Roberts et al. 2016), and television characters (e.g., Xena, Warrior Princess, Elthusa xena; van der Wal et al. 2019). There is room for creativity and exploration in parasitology, as many currently undescribed species still await discovery. ...
... Gnathia marleyi (Farquharson, Smit & Sikkel, 2012) is a common gnathiid isopod in shallow reefs in the Caribbean. Gnathia marleyi is most active at night and during crepuscular hours, with peak activity varying among the three feeding stages (Sikkel et al., 2006(Sikkel et al., , 2009 and it has been confirmed to feed on at least 42 different species of fishes (Farquaharson et al., 2012;Coile & Sikkel, 2013;Hendrick et al., 2019;G. ...
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Gnathiid isopods are one of the most abundant groups of ectoparasites on coral reef fishes. They, and other isopods, have been shown to significantly affect the health and behaviour of many reef fish. Whether isopod emergence differs among habitats on coral reefs is not known. In this study, we measured emergence rates of parasitic isopods (Gnathiidea and Flabellifera) in six habitats at two sites at Lizard Island during new moon periods in March and December 2004. Isopods were collected from the periphery and centres of micro-reefs, patch reefs, continuous reefs, and from inter-reefal habitats (sand or rubble) with 1 m(2) emergence traps. Sites (Casuarina and Coconut Beach) were located on opposite sides of Lizard Island. Live gnathiids were collected with light traps in November 2005 to investigate species differences between sites. At both sites, the most abundant gnathiid species was exclusive to that site. More gnathiid larvae emerged at night, and emergence of fed gnathiids (pranizae) and flabelliferan isopods was almost exclusively nocturnal. Diurnal emergence was greater at Coconut Beach than Casuarina Beach. Although emergence counts were not consistently affected by parameters such as habitat, site, or sampling period, gnathiid size and feeding state were. Where significant differences existed, gnathiids were larger and more often fed over reef borders than centrally. We suggest first stage larvae (Z1) have the largest influence on total abundance and are patchily distributed in accordance with adults from which they have recently hatched. As later stage larvae depend on fish, more successful (fed) and older larvae are found on the edges of reefs where appropriate hosts may be more abundant, or predation is lower. Gnathiids were over-dispersed in all habitats investigated, including apparently homogeneous beds of coral rubble and sand. This indicates that their distributions may be better predicted by very fine scale differences in substrate or that aggregations are the result of gregariousness and may be difficult to predict on the basis of substrate. Emergence traps collected comparatively few parasitic flabelliferan isopods. This community differed greatly from the previously described community of scavenging isopods at Lizard Island. These differences are probably the result of differences in trapping methodology.
Article
One new genus, Chalixanthura, and twenty-four new species of isopods are described and figured. These include Chalixanthura scopulosa, Eisothistos petrensis, Accalathura setosa, Apanthura cracenta, Pendanthura hendleri, Cymodoce ruetzleri, Dynamenella quadrilirata, Paracerceis cohenae, Paracerceis glynni, Metacirolana agaricicola, Metacirolana halia, Metacirolana menziesi, Gnathia rathi, Astacilla regina, Stenetrium bowmani, Stenetrium patulipalma, Stenetrium spathulicarpus, Bagatus punctatus, Angliera psamathus, Microcharon sabulum, Joeropsis bifasciatus, Joeropsis personatus, Munna petronastes, and Microcerberus syrticus. Figures and/or descriptions are also provided for Stenetrium minocule Menzies and Glynn, Stenetrium stebbingi Richardson, Joeropsis coralicola Schultz and McCloskey, and Joeropsis rathbunae Richardson. With a few exceptions, all material comes from the coral reef system at Carrie Bow Cay, Belize. Depth and ecological data, where available, are provided.