Zootaxa 1525: 41–49 (2007) ISSN 1175-5326 (print edition) www.mapress.com/zootaxa/ ZOOTAXA Copyright © 2007 · Magnolia Press ISSN 1175-5334 (online edition) Homalometron moraveci n. sp. (Digenea: Apocreadiidae) in the yellowfin goatfish, Mulloidichthys vanicolensis (Valenciennes, 1831) (Perciformes: Mullidae), from New Caledonia and the Great Barrier Reef, with a checklist of digeneans of Mulloidichthys species RODNEY A. BRAY1, JEAN-LOU JUSTINE2 & THOMAS H. CRIBB3 1Department of Zoology, Natural History Museum, Cromwell Road, London SW7 5BD, UK. Email: [email protected] 2Équipe Biogéographie Marine Tropicale, Unité Systématique, Adaptation, Évolution (CNRS, UPMC, MNHN, IRD), Institut de Recherche pour le Développement, BP A5, 98848 Nouméa Cedex, Nouvelle-Calédonie. E-mail: [email protected] 3Centre for Marine Studies and Department of Microbiology and Parasitology, The University of Queensland, Brisbane, Queensland 4072, Australia. E-mail: [email protected] Abstract Homalometron moraveci n. sp. is described from the yellowfin goatfish, Mulloidichthys vanicolensis, from the waters off New Caledonia and from the Swain Reefs of the Great Barrier Reef. Its unique combination of narrow, elongate body and long hermaphroditic duct reaching well into the hindbody, distinguish this species from all other species of Homa- lometron. A checklist of species of digeneans reported in species of Mulloidichthys shows that most of the records are of members of the Opecoelidae and this is the first record of an apocreadiid from this host genus. Key words: Digenea, Apocreadiidae, Homalometron moraveci n. sp., Mullidae, Mulloidichthys, New Caledonia, Great Barrier Reef Résumé Homalometron moraveci n. sp. est décrit de Mulloidichthys vanicolensis de Nouvelle-Calédonie et des Swain Reefs du Récif de la Grande Barrière, Australie. L’espèce est distinguée de tous les autres Homalometron par sa combinaison unique de caractères, son corps allongé et étroit et son long canal hermaphrodite continuant bien dans l’arrière du corps. Une liste des espèces de digènes mentionnées chez les espèces de Mulloidichthys montre que la plupart sont des Ope- coelidae, et que ceci constitue la première mention d’un Apocreadiidae dans ce genre d’hôte. Introduction Members of the mullid genus Mulloidichthys Whitley, 1929 are widespread in tropical reef waters of the Atlantic, Indian and Pacific Oceans. We have recovered, and report on here, specimens of the apocreadiid genus Homalometron Stafford, 1904 in the yellowfin goatfish Mulloidichthys vanicolensis (Valenciennes, 1831) from off New Caledonia and from the Swain Reefs in the southern Great Barrier Reef. As far as we are aware this is the first record of an apocreadiid in a member of the family Mullidae (Cribb & Bray 1999). The only previous record of a digenean from M. vanicolensis is that of a sanguinicolid blood-fluke Phthinomita sp. B, from Lizard Island in the northern Great Barrier Reef (Nolan & Cribb 2006). Some confusion exists in the identity of these goatfishes and it is likely that some records of digeneans from other named species of Mul- loidichthys actually refer to records from M. vanicolensis. Accepted by N. Dronen: 17 May 2007; published: 12 Jul. 2007 41 Materials and methods Digeneans collected from freshly killed fish were fixed by being pipetted into hot boiling seawater or saline and immediately preserved in ethanol or formalin. Whole-mounts were stained with Mayer's paracarmine, cleared in beechwood creosote and mounted in Canada balsam. Measurements were made through a drawing tube on an Olympus BH-2 microscope, using a Digicad Plus digitising tablet and Carl Zeiss KS100 software adapted by Imaging Associates, and are quoted in micrometres, with the range and the mean in parentheses (Table 1). The following abbreviations are used: BMNH, the British Museum (Natural History) Collection at the Natural History Museum, London, UK; MNHN, Muséum National d’Histoire Naturelle, Paris, France; QM, Queensland Museum Collection, Brisbane, Australia. TABLE 1. Dimensions of Homalometron moraveci n. sp. from two localities. Locality New Caledonia Swain Reefs n72 Length 3,399–5,881 (4,359) 3,631–3,947 Width 235–396 (319) 307–315 Forebody 904–1,469 (1,104) 958–1,072 Pre-oral lobe 0–36 (8) 7–10 Oral sucker 91–169 x 94–174 (130 x 138) 133–134 x 133–140 Prepharynx 179–326 (237) 233–253 Pharynx 64–117 x 58–81 (91 x 67) 84–86 x 78 Oesophagus 40–129 (80) 40–98 Intestinal bifurcation to ventral sucker 453–748 (565) 463–516 Vitellarium to ventral sucker 302–620 (454) 307–342 Ventral sucker (VS) 151–188 x 137–203 (171 x 175) 159–164 x 171–177 Hermaphroditic duct 308–396 (355) 301–372 Encroachment of hermaphroditic duct into hindbody 119–163 (159) 101–191 Pars prostatica 102–310 (234) 214–243 Seminal vesicle (SV) 122–275 x 64–137 (194 x 114) 99–200 x 84–153 Extent of SV into hindbody 426–722 (559) 490–504 Ventral sucker to ovary 628–1,119 (838) 707–722 Ovary 100–189 x 86–175 (149 x 142) 125–130 x 114–125 Ovary to Anterior testis 0–7 (1) 9–10 Anterior testis 222–367 x 122–261 (287 x 204) 234–253 x 171–174 Distance between testes 0–94 (32) 5–56 Posterior testis 268–457 x 141–281 (337 x 221) 264–275 x 171–178 Post-testicular region 924–2,068 (1,437) 1,126–1,291 Post-caecal region 192–320 (264) 136–213 (168) Eggs 59–80 x 34–54 (74 x 45) non-ovigerous Width as % of body-length 6.38–8.53 (7.40) 7.77–8.68 Forebody as % of body-length 22.3–28.5 (25.6) 26.4–27.2 Sucker-length ratio 1:1.04–2.00 (1.37) 1:1.19–1.23 Sucker-width ratio 1:1.10–1.97 (1.32) 1:1.27–1.29 Oral sucker:pharynx 1:1.56–2.49 (2.05) 1:1.71–1.80 VS to ovary as % of body-length 16.4–21.2 (19.1) 18.3–19.5 VS to SV as % of VS to ovary 58.7–72.2 (67.2) 67.9–71.3 Post-testicular region as % of body-length 27.2–38.9 (32.7) 31.0–32.7 42 · Zootaxa 1525 © 2007 Magnolia Press BRAY ET AL. New Caledonian M. vanicolensis specimens ranged 220–280 mm in fork-length, infected host 240mm; the Australian host was 285mm. Results Family Apocreadiidae Skrjabin, 1942 Subfamily Apocreadiinae Skrjabin, 1942 Genus Homalometron Stafford, 1904 Homalometron moraveci n. sp. (Figs 1–3) Type-host: Mulloidichthys vanicolensis (Valenciennes, 1831), Mullidae, yellowfin goatfish. Site: Digestive tract. Type-locality: Fish market, Nouméa, allegedly from off Bouraké, Commune de Boulouparis, New Cale- donia (21°58’S, 166°00’E) (21/09/2006). Other locality: Swain Reefs, Great Barrier Reef (21°53’S, 152°21’E, Feb., 2003). Prevalence: New Caledonia, 25% (1 of 4); Swain Reefs, 100% (1 of 1). Type-specimens: New Caledonia: Holotype MNHN JNC1966-1, paratypes MNHN JNC1966-2–8, BMNH 2007.5.1.1–5, QM G223078; Swain Reefs: paratypes QM G223079, BMNH 2007.5.1.6. Etymology: The species is named for Dr Frank Moravec (České Budějovice, Czech Republic) in recogni- tion of his major contributions to fish parasitology, and as he was involved in the collection of the specimens. Description. Based on 11 complete worms and several fragments from New Caledonia and 2 well-devel- oped, but non-ovigerous, worms from Swain Reefs. Measurements in Table 1. Body-elongate, narrow. Tegu- ment spinous, spines reach to posterior extremity, sparse in hindbody. Pre-oral lobed short or absent. Oral sucker subglobular, mouth subterminal. Ventral sucker rounded to oval, slightly to distinctly larger than oral sucker. Forebody relatively short. Prepharynx long. Pharynx oval, small. Oesophagus distinct. Intestinal bifur- cation in mid-forebody. Caeca long, narrow, terminate blindly, unequal, slightly separated from posterior extremity. Testes two, oval with long axis longitudinally, entire, tandem, contiguous to distinctly separate, in mid- hindbody. Seminal vesicle oval, about halfway between ventral sucker and ovary. Pars prostatica long, nar- row, sheath of gland cells difficult to distinguish from other gland-cells scattered in parenchyma, some evi- dence in some specimens of slightly denser packing of cells in this region, enters hermaphroditic duct distinctly posterior to ventral sucker. No ejaculatory duct or cirrus detected. Hermaphroditic duct long, nar- row, passes dorsally to ventral sucker, distinctly into hindbody (Table 1). Genital pore opens in median line immediately anterior to ventral sucker. Ovary subglobular to oval, pretesticular, contiguous with or slightly separated from anterior testis. Semi- nal receptacle canalicular, oval, mostly pretesticular. Laurer’s canal opens dorsally to ovary. Mehlis’ gland preovarian. Uterus preovarian, intercaecal. Metraterm not strongly differentiated, starts at about posterior level of seminal receptacle, walls narrow. Eggs few, large, operculate, with thin, tanned shells. Vitellarium fol- licular, anterior extent in region of seminal vesicle, ventral, dorsal and lateral to caeca, not overlapping gonads, may have gaps at or around ovarian level, confluent dorsally and ventrally in post-testicular region. Excretory pore terminal. Vesicle I-shaped, reaches almost to posterior testis. Lymphatic vessels not detected. HOMALOMETRON MORAVECI N. SP. FROM GOATFISH Zootaxa 1525 © 2007 Magnolia Press · 43 FIGURES 1–3. Homalometron moraveci n. sp. 1. Holotype, ventral view, New Caledonia. 2. Ventral view, immature specimen, Swain Reefs. 3. Terminal genitalia, lateral view, New Caledonia. 4. Proximal female system in immature spec- imen, Swain Reefs, dorsal view. Abbreviations: LC, Laurer’s canal; M, metraterm; O, ovary; PP, pars prostatica; SR, seminal receptacle; SV, seminal vesicle; T, testis; U, uterus; V, vitellarium; VR, vitelline reservoir. Scale-bars: 1, 2, 1000μm; 3, 200μm; 4, 100μm. 44 · Zootaxa 1525 © 2007 Magnolia Press BRAY ET AL. Discussion This species fits into the concept of Homalometron Stafford, 1904 espoused by Cribb & Bray (1999) and Cribb (2005).