The Lepocreadiidae (Digenea) of pomacentrid fishes (Perciformes) from Heron Island, Queensland, Australia

Systematic Parasitology26: 189-200, 1993. © 1993 KluwerAcademic Publishers. Printedin the Netherlands.

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The Lepocreadiidae (Digenea) of pomacentrid fishes (Perciformes) from Heron Island, Queensland, Australia Rodney A. Bray 1, Thomas H. Cribb 2 and Stephen C. Barker 3 1 Department of Zoology, The Natural History Museum, Cromwell Road, London SW 7 5BD, UK 2Queensland Museum, PO Box 300, South Brisbane, Queensland 4101, Australia 3Department of Parasitology, University of Queensland, Brisbane, Queensland 4072, Australia Accepted for publication 20th October, 1992

Abstract

The following lepocreadiid species are described from pomacentrid fishes from the Southern Great Barrier Reef at Heron Island, Queensland: Lepocreadium adlardi n. sp. from Abudefdufbengalensis; L. clavatum from Acanthochromis polyacanthus and Parma polylepis; Lepocreadium sp. from Amblyglyphidodon curacao; Lepocreadium sp. from Pomacentrus cf. wardi; Preptetos xesuri (new synonyms: P. caballeroi, P. pritchardae Toman, 1989 nec Ahmad, 1984) from Parma polylepis plus the acanthurid Naso annulatus; and P. cannoni from Pomacentrus bankanensis.

Introduction

This paper is a further contribution to the study of the digenean fauna of fishes of the Great Barrier Reef. Hitherto, we have presented several contributions, including one on members of the superfamily Hemiuroidea from pomacentrid fishes, i.e. damselfishes, from Heron Island (Bray, Cribb & Barker, 1993). The present paper sets out to report on another digenean group, the family Lepocreadiidae, from the pomacentrids. Members of the perciform family Pomacentridae have been reported in the literature as hosts of six lepocreadiid species, five of which belong to the genus Lepocreadium Stossich, 1904. These reports are of Lepocreadium album (Stossich, 1890) in Chromis chromis from the Mediterranean Sea off Greece (Papoutsoglou, 1976), L. clavatum Ozaki, 1932 in Dascyllus albisella from Hawaii (Pritchard, 1963), L. oyabitcha Machida, 1984 in Abudefduf vaigiensis from Japan (Machida, 1984), L. sogandaresi Nahhas & Powell, 1971 in Eupomacentrus leuco-

stictus from Florida (Nahhas & Powell, 1971) and L. trulla (Linton, 1907) in Chromis multilineatus from Puerto Rico (Dyer et al., 1985). The sixth species reported is Aephnidiogenes dollfusi Razarihelisoa, 1959 (a synonym of A. senegalensis Dollfus & Capron, 1958 according to Fischthal & Kuntz, 1964) in Abudefduf sexfasciatus from Madagascar (Razarihelisoa, 1959).

Materials and methods

Pomacentrids were collected by the authors (unless otherwise stated) at Heron Island (23029 ' S, 151°55 ' E) during January 1991 and January 1992. Host identifications were based on Randall, Allen & Steene (1990) with some reference to Allen (1975). Our identifications were confirmed and aided by Mr Jeff Johnson of Queensland Museum. Voucher specimens of pomacentrids were donated to the Queensland Museum and are listed in Bray, Cribb & Barker (1993).

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The digeneans collected by the authors were from freshly killed fish hosts and were fixed by being pipetted into nearly boiling 5% formalin. Whole-mounts were stained with Mayer's acid haemalum, cleared in methyl salicylate and mounted in Canada balsam. Measurements are quoted as ranges with means in parentheses and are in micrometres. The following abbreviations are used: BM(NH), the British Museum (Natural History) collection at The Natural History Museum, London; HWML, Harold W. Manter Laboratory, Lincoln, Nebraska; MPM, Meguro Parasitological Museum, Tokyo; NSMT, National Science Museum, Tokyo; QM, Queensland Museum, Brisbane; SAM, South Australian Museum, Adelaide; THC, the Cribb autopsy number series. Distribution lists are set out and numbered in accordance with the FAO Major Fishing Areas (Couper, 1989).

Family Lepocreadiidae Odhner, 1905 Subfamily Lepoereadiinae Odhner, 1905

Genus Lepocreadium Stossich, 1904 Synonym: Lepotrema Ozaki, 1932 This genus contains about 30 species, but it has never been critically revised. Edwards & Nahhas (1968) presented a key to 23 species, some of which are not now considered to be members of this genus. Species omitted from the key, for various reasons, include L. angelae Kruse, 1981, L. areolatum (Linton, 1900), L. caballeroi Sogandares-Bernal & Hutton, 1960, L. dongxiangensis Wang, 1989, L. drepanei Shen, 1990, L. manteri Olson, 1978, L. kamegaii Shimazu & Nagasawa, 1985, L. navodoni Shen, 1986, L. oyabitcha Machida, 1984, L. panajiense Gupta & Sayal, 1979, L. pegorchis (Stossich, 1900), L. serospinosum Nicoll, 1909, L. sogandaresi Nahhas & Powell, 1971, L. trachinoti Wang, 1989 and L. xanthichthydis Yamaguti, 1970.

Lepocreadium adlardi n. sp. (Figs 1-2) Material studied Type-host: Abudefduf bengalensis (Bloch). Intestine. THC Nos 3232 (2 imm.), 3348 (4, 1 imm.), 3426 (4), 3430 (2, 1 imm.). Holotype QM GL 14763, paratypes QM GL 14764-8. BM(NH) 1992.10.5.1-2. Description Based on 8 adult worms, 7 measured. Body elongate; 1,099-1,224 x 235-284 (1,151 x 262); forebody slightly narrower than hindbody, attenuated (Fig. 1). Tegument spinous throughout. Scattered granules of eye-spot pigment in lateral forebody from level of prepharynx to intestinal bifurcation. Scattered small gland-cells throughout parenchyma, small group clustered around oesophagus. Pre-oral lobe distinct; 11-22 (15). Oral sucker large; transversely oval; subterminal; 97106 × 129-140 (102 x 134). Ventral sucker rounded; in about mid-body; 109-155 × 121-155 (134 × 134). Sucker-width ratio 1:0.90-1.20 (1.00). Forebody 40-48 (43)% of body-length. Prepharynx long; 113-155 (134); narrow. Pharynx elongate-oval; 97-126 × 68-103 (108 × 84). Oesophagus distinct; 45-64 (55) long; 31-53 (42)% of prepharynx length. Intestinal bifurcation in posterior forebody, 74-116 (83) from ventral sucker. Caeca rectilinear; terminate blindly 52100 (68) from posterior extremity. Testes rounded; tandem, adjacent; intercaecal; in mid-hindbody; anterior 105-119 x 108-138 (112 × 124); posterior 119-138 × 100-135 (129 x 119). Post-testicular region 15-17 (16)% of body length. External seminal vesicle broadly tubular, convoluted; without associated glandcells; often partly obscured by eggs. Cirrus-sac large; lies longitudinally with distal extremity turned ventrally; 144-187 × 39-60 (172 × 52); reaches 5-32 (25) into hindbody (Fig. 2a). Internal seminal vesicle globular; proximal. Pars prostatica vesicular; oval; lined with anuclear cell-like bodies; surrounded by gland-cells embedded in connective tissue, gland-cells also extend around internal seminal vesicle and ejaculatory duct.

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I Figs 1-5. 1. Lepocreadium adlardi n. sp. Holotype (THC No. 3426), ventral view, uterus in outline only. 2. L. adlardi. A. Terminal genitalia, ventral view (THC No~ 3348). B. Detail of distal metraterm and folded muscular pad. 3. L. clavatum Ozaki from Acanthochromis polyacanthus (THC No. 3365). Ventral view, uterus in outline only. 4. L. clavatum from Parma polylepis (THC No. 3486). Terminal genitalia, ventral view. 5. L. clavatum from A. polyacanthus (THC No. 3124). Ventral view of immature worm showing extent of excretory vesicle. Scale-bars: 1,3,5, 200 Ixm; 2,4, 100 ~m.

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Ejaculatory duct convoluted; thick-walled distally; opens through small papilla into genital atrium; everted cirrus not seen. Genital atrium large. Genital pore overlies left caecum, close to anterosinistral margin of ventral sucker. Ovary tri-lobed; dextrally submedian, immediately pretesticular. 19-55 (38) from ventral sucker; 66-94 × 61-101 (83 x 82). Seminal receptacle in dorsal plane, overlapping anterior edge of anterior testis. Mehlis' gland and vitelline reservoir dorsal to ovary. Laurer's canal opens dorsally to middle of anterior testis. Uterus intercaecal; posterior extremity overlaps anterior testis; anterior limit at about posterior margin of ventral sucker. Eggs few (3-8); large; tanned; operculate; 52-64 × 27-39 (59 × 34). Metraterm distinct; almost equal in length to cirrus-sac; runs parallel and ventrally to cirrus-sac; distal region forms loop to enter genital atrium through slit anterior to cirrus-sac; distal extremity clamped in prominent folded muscular pad (not a sphincter) (Fig. 2b). Vitellarium follicular; in lateral fields; anterior extremity of lateral fields at about intestinal bifurcation or close to anterior margin of ventral sucker, between 84 anterior to and 11 posterior to anterior margin of ventral sucker; fields reach close to posterior extremity; present ventral and lateral, not dorsal, to caeca, but narrow rows of follicles lie along internal edge of caeca dorsally to ovary and testes; fields confluent ventrally in post-testicular region. Excretory pore mid-dorsal, close to level of posterior extremity of caeca. Vesicle I-shaped, usually reaches to about middle of ventral sucker or just anterior; in one specimen does not quite reach to ventral sucker.

Discussion This species does not key down satisfactorily in Edwards & Nahhas' (1968) key. It belongs to a small group of Lepocreadium species which share the feature described here as a folded muscular pad surrounding the distal metraterm. These indude L. clavatum Ozaki, 1932, L. incisum Hanson, 1955 and L. xanthichthydis Yamaguti, 1970. These three species are predominantly or solely

parasites of fishes of the family Monacanthidae. L. adlardi n. sp. differs from these in its elongate forebody, long prepharynx and less extensive vitellarium. The species L. angelae Kruse, 1981 from Scorpis georgianus from South Australia has a similarly elongate prepharynx, but apparently lacks the folded muscular metraterm pad, although the metraterm is described as 'conspicuous'. No indication of this pad was detected in 12 paratype specimens (SAM V2753-64) of L. angelae. This species also differs from L. adlardi in its sucker-ratio (1 : 2.4), the small size of the suckers relative to body length, the excretory vesicle reaching into the forebody and the small eggs (Kruse, 1981). This species is named after our colleague Dr Rob Adlard of the University of Queensland, in recognition of, and in gratitude for, his invaluable contributions to this project.

Lepocreadium clavatum (Ozaki 1932) Yamaguti,

1938 (Figs 3-5) Synonym: Lepotrema clavatum Ozaki, 1932 Material studied Acanthochromis polyacanthus (Bleeker). Intestine. THC Nos 3064 (1), 3123 (4, 1 imm.), 3124 (3 imm.), 3361 (1), 3363 (2), 3364 (1), 3365 (1), 3372 (1), 3407 (1). QM GL 14769-72. BM(NH) 1992.10.5.3-5. Parma polylepis Gtinther. Intestine. THC Nos 3464 (1), 3486 (3, l imm.). QM GL 14773-4, BM(NH) 1992.10.5.6. Description Based on 16 worms, measurements of 9 from A. polyacanthus and, following comma, those of 3 from P. polylepis. Body elongate oval; rounded at both ends (Fig. 3); 834-1,447× 335-642 (1,131 × 430), 846-1,148 × 334-444. Tegument spinous to about mid-hindbody. Sparse scattering of eye-spot pigment granules in region lateral to prepharynx, pharynx and oesophagus. Small, scattered gland-cells throughout parenchyma, with small clusters around posterior prepharynx and oesophagus. Pre-oral lobe distinct, 3-31 (15), 13-

Lepocreadiids of pomacentrid fishes 16 long. Oral sucker transversely elongate; aperture subterminal; 90-152 x 143-225 (117 × 169), 109-135 x 142-193. Ventral sucker rounded; just within anterior half of body; 113-174 x 112-196 (137 × 146), 126-160 × 124-183. Sucker-width ratio 1:0.78-0.95 (0.87), 0.87-0.95. Forebody 29-42 (38), 38-41% of body length. Prepharynx always distinct, with internal muscular wall and less dense external muscular thickening; 35-64 (47), 22-39 long. Pharynx oval; large; 66116 x 80-177 (91 x 104), 77-103 x 77-117. Oesophagus with relatively thin, muscular wall surrounded by gland-cells; 42-64 (54), 42-67 long; 75-183 (123), 123-304% of prepharynx length. Intestinal bifurcation in posterior half of forebody, 87-148 (126), 84-106 from ventral sucker. Caeca wide; rectilinear; terminate blindly just beyond testes at 69-116 (91), 64-90 from posterior extremity. Testes oval to rounded; margin smooth or slightly irregular; slightly oblique; adjacent; in mid hindbody; anterior 87-140 × 96-138 (112 x 116), 90-116 × 89-125; posterior 105-180 x 94-196 (136 × 124), 113-148 × 98-132. Post-testicular region 13-18 (16), 15-17% of body-length. External seminal vesicle saccular; without associated gland-cells; often obscured by eggs. Cirrus-sac large; recurved at about middle or distally; wall muscular; overall length 158-290 (205), 167-215, width 55-116 (76), 58-83; usually reaches into hindbody, up to 93, 19, but occasionally may not quite reach posterior margin of ventral sucker; contains fibrillar connective tissue and scattered prostatic gland-cells (Fig. 4). Internal seminal vesicle small; globular; proximal; thick-walled. Pars prostatica vesicular; oval. Ejaculatory duct long; convoluted; muscular; no prominent cirrus seen. Genital atrium distinct. Genital pore overlying sinistral caecum ventrally; antero-sinistral to ventral sucker. Ovary trilobed; immediately pretesticular; 35100 (58), 10-42 from ventral sucker, or occasionally just overlapping ventral sucker; 84-164 x 97132 (117 × 117), 69-119 x 100-116. Mehlis' gland antero-sinistral to ovary. Vitelline reservoir postero-dorsal to ovary. Laurer's canal opens dorsally at level of about middle or posterior part of an-

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terior testis, dorsal to sinistral extremity of testis or just sinistral to testis. Much of female system obscured by eggs. Seminal receptacle saccular; dorsal to ovary. Uterus intercaecal; from anterior testis, which it often overlaps to dorsal to ventral sucker. Eggs numerous; tanned; operculate; large, 56-76 x 32-43 (63 × 36), 58-71 × 32-39 (64 x 35). Metraterm distinct; slightly shorter than cirrus-sac; walls thick, muscular; proximal part runs parallel and ventral to cirrus-sac; distal part runs dorsal to recurved distal cirrus-sac; enters genital atrium through narrow slit bounded by large, circular, folded muscular pad (not a sphincter). Vitellarium follicular; in lateral fields; anterior limit at level of posterior margin of pharynx or anterior oesophagus, 116-225 (180), 129180 from ventral sucker; fields reach to close to posterior extremity; mainly in ventral plane; narrow confluence in forebody; ventral and lateral, not dorsal, to caeca; not encroaching between gonads; fields confluent in post-testicular region. Excretory pore mid-dorsal, about halfway between caecal ends and posterior extremity. Vesicle I-shaped; reaches to intestinal bifurcation in immature worms (Fig. 5) and, where seen in mature worms, reaches level between just anterior to middle of ventral sucker and just into forebody.

Type-host and locality: Monacanthus cirrhifer, Otaru to Nagasaki region, Japan. Records: 1. Ozaki (1932); 2. Yamaguti (1934); 3. Ozaki (1936); 4. Yamaguti (1938); 5. Hanson (1955); 6. Pritchard (1963); 7. Ichihara (1968); 8. Yamaguti (1970); 9. Dyer, Williams & Williams (1988); 10. Present study. Descriptions: 1,2,4,8,10. Definitive hosts: Balistidae: Melichthys buniva (5,6), M. vidua (6,8), Rhinecanthus aculeatus (9). Bothidae: Pseudorhombus cinnamoneus (2). Chaetodontidae: Hemitaurichthys zoster (6). Monacanthidae: Monacanthus [or Stephanolepis] cirrhifer (1,2,4,7), Thamnaconus [or Cantherines, or Navodon] modestus [= C. unicornu] (2,3,4,10). Pomacentridae: Acanthochromis polyacanthus (10), Dascyllus albisella (6), Parma polylepis (10). Distribution: FAO Fisheries Area 61 Pacific, NW

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[Japan (1,2,3,4,7,9,10), 71 Pacific W. Central [Queensland (10)], 77 Pacific, E Central [Hawaii (5,6,8)].

Discussion Using the key of Edwards & Nahhas (1968), this species keys down to L. clavatum, a parasite reported mainly in monacanthid fishes, but our worms differ from the published descriptions in the length of the prepharynx and the slightly larger eggs. Examination of specimens from monacanthids has shown, however, that these differences do not stand up to scrutiny and that our specimens must be considered to be conspecific with these specimens. The specimens we have examined are: MPM 30029, 13 immature and seven mature whole-mounted specimens and five sets of serial sections from Monacanthus cirrhifer, Hiroshima, Japan. These are Ozaki's specimens, but according to Shimazu (pers. comm.) it is not possible to say whether they are the types. The specimens are flattened and poorly fixed, but the prepharynx is distinct, although sometimes forced into the oral sucker or pharynx by the flattening. Where the prepharynx is distinct it measures 32-76 long. The eggs are weakly tanned in most specimens and measure 54-60 long. The serial sections indicate that the excretory vesicle reaches into the forebody, as in some of our specimens. MPM 30030, six gravid whole-mounts from Thamnaconus [or Cantherines] modestus, collected by Ozaki, but with no further data. Shimazu (pers. comm.) suggested that that may be from Hiroshima, as Ozaki (1936, p. 515) stated that L. clavaturn was often obtained along with Leptocreadium skrjabini Ozaki, 1936 from this host and locality. These flattened specimens had a prepharynx 1996 long and eggs 54-64 long. NSMT-P1 3697-3699, 64 flattened whole-mounts, collected by Dr T. Shimazu from Thamnaconus modestus, Moroiso Bay, Misaki, Kanagawa Prefecture, Japan in 1987 and 1988. The prepharynx is distinct, 45-95 long. The eggs are 57-64 long. We have also examined the specimens (HWML 1681) reported from the pomacentrid Dascyllus

albisella from Hawaii by Pritchard (1963). These two flattened specimens are in general morphology indistinguishable from our specimens. The length of the prepharynx (0-45) is distorted by flattening and the eggs at 51-54 long are slightly shorter than in our specimens. L. navodoni Shen, 1986, which is reported from the monacanthid Navodon modestus in the East China Sea and may well be a synonym of L. clavatum, is described as having a prepharynx 34-71 long, but eggs only 48-54 × 24-27 (Shen, 1986). Also similar, and possibly a synonym of L. clavatum, is Preptetos cylindricus Wang, 1989 from the monacanthids Navodon septentrionalis and Monacanthus chinensis from the East China Sea, but the ovary was described and figured as unlobed (Wang, 1989). This species does not have the characters of Preptetos. This species was originally erected as the typespecies of the genus Lepotrema Ozaki, 1932, considered since Yamaguti (1938) a synonym of Lepocreadium. Ozaki (1932) distinguished Lepotrema from Lepocreadium (and some other lepocreadiine genera) 'mainly' on the lateral position of the genital pore and the presence of the genital sucker. Yamaguti (1938), in sinking Lepotrema, pointed out that the genital pore usually lies 'to one side of the median line in this subfamily' and that the 'genital sucker' is a misnomer, referring to 'a bulb-like muscular thickening of the metraterm' (our 'folded muscular pad'). Other unusual features are exhibited by L. clavatum, such as the distinctly dorsal excretory pore and the trilobed ovary. The recent redescriptions of the type-species of Lepocreadium, L. album (Stossich, 1890), by Radujkovic, Orecchia & Paggi (1989) and Fares & Maillard (1990), gives an opportunity to reassess the status of Lepotrema. In L. album the genital pore is lateral (distinctly in Fares & Maillard, 1990, less so in Radujkovic et al., 1989), the excretory pore is terminal, the ovary is unlobed and the metraterm is unelaborated. The three latter characters could be considered to distinguish Lepotrema and Lepocreadium, but the finding of the single Lepocreadium specimen from Pomacentrus cf. wardi (below), with a dorsal excretory pore, a globular

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ovary and a weakly elaborated metraterm indicates that Lepocreadium (sensu lato) contains forms with an assortment of these characters. According to Edwards & Nahhas' (1968) key, several species of Lepocreadium have lobed ovaries, some of which have a terminal excretory pore and an unelaborated metraterm ( e . g . S . trulla (Linton, 1907) and L. floridanum Sogandares-Bernal & Hutton, 1969). At present we see no pressing reason for re-erecting the genus Lepotrema although as the genus grows and knowledge of the group deepens, it may be necessary to reassess this view.

Discussion

Lepocreadium sp. (Figs 6-7)

Lepocreadium sp. (Figs 8-9)

Material studied Amblyglyphidodon curacao (Bloch). Intestine.

Material studied Pomacentrus cf. wardi Whitley. Intestine. THC

THC Nos 1857(1), 3120(1). QM GL 14775-6.

No. 3268 (1). QM GL 14777.

These two specimens, collected from different host specimens in different years, are similar to L. clavatum in many metrical features and possess a distinct folded muscular metraterm pad. They differ in the short cirrus-sac, just overlapping the ventral sucker, and the straight ejaculatory duct (Fig. 7). More specimens are needed to ascertain the status of this form.

Description Description Measurements taken from two worms and some descriptive details are: Body 859-1,367 x 353-559 (Fig. 6). Pre-oral lobe 0-7. Granules of eyespot pigment sparse in forebody. Gland-cells scattered throughout parenchyma. Oral sucker 109-154 × 148-167. Ventral sucker 128-168 x 141-171. Sucker-ratio 1:0.951.02. Forebody 35-38% of body length. Prepharynx 29-87. Pharynx 83-113 × 80-85. Oesophagus 35-73; 84-121% of prepharynx length. Intestinal bifurcation 51-87 from ventral sucker. Caeca end 71-122 from posterior extremity. Testes: anterior 95-109 x 116, posterior 108-148 x 124-150. Post-testicular region 19-20% of body-length. External seminal receptacle without associated gland-cells. Cirrus-sac 103-135 x 52-55, terminating 55-71 anterior to posterior edge of ventral sucker. Ovary trilobed; 77-106 x 103-126; 3-80 from ventral sucker. Eggs 51-61 x 26-42 (56 × 31). Vitellarium extends to level of mid or anterior pharynx, 127-248 from ventral sucker. Excretory pore dorsal, between caecal ends. Excretory vesicle reaches at least to ovary, anterior extent not seen.

The measurements of this single worm and some descriptive details are: Body 890 x 309 (Fig. 8). Pre-oral lobe 13. Eyespot pigment granules sparse in forebody. Glandcells scattered throughout parenchyma, clustered around anterior pharynx and oesophagus. Oral sucker 97 x 130. Ventral sucker 129 x 132. Sucker-ratio 1:1.02. Forebody 36% of bodylength. Prepharynx 42. Pharynx 77 x 71. Oesophagus 32, 76% of prepharynx length. Intestinal bifurcation 63 from ventral sucker. Caeca reach to 55-58 from posterior extremity. Testes: anterior 84 x 71, posterior 80 x 74. Post-testicular region 17% of body-length. Most of external seminal vesicle obscured by eggs, no evidence of associated gland-cells. Cirrus-sac 113 x 35, reaches to 18 from posterior margin of ventral sucker (Fig. 9). Ovary smoothly rounded; 74 x 71; 98 posterior to ventral sucker. Eggs 65-71 x 32-35. Vitellarium reaches to posterior pharynx, 109 from ventral sucker. Excretory pore dorsal, between caecal ends. Excretory vesicles reaches at least to ovary, anterior extent not seen.

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Figs 6-10. 6. Lepocreadium sp. from Amblyglyphidodon curacao (THC No. 1857). Ventral view, uterus in outline only. 7. Lepocreadium sp. from A. curacao (THC No. 1857). Terminal genitalia, ventral view. 8. Lepocreadium sp. from Pomacentrus cf. ward (THC No. 3268). Ventral view, uterus in outline only. 9. Lepocreadium sp. from P. cf. wardi (THC No. 3268). Terminal genitalia, ventral view, external seminal vesicle partly obscured by eggs. 10. Preptetos xesuri (Yamaguti) from Parma polylepis (THC No. 3324). Ventral view, uterus in outline only. Scale-bars: 6,8,10, 200 izm; 7,9, i00 p,m.

Lepocreadiids of pomacentrid fishes Discussion

This single worm differs from the others reported here from pomacentrids by combinations of the following features: rounded ovary; short cirrussac; short straight ejaculatory duct; large ventral sucker to ovary distance; no folded, muscular metraterm pad present (a narrow sphincter only is seen); and egg-size.

Genus Preptetos Pritchard, 1960

Preptetos xesuri (Yamaguti, 1940) Pritchard, 1960 (Fig. 10) Synonyms: Opechona xesuri Yamaguti, 1940; Lepocreadium xesuri (Yamaguti, 1940) Montgomery, 1957; Preptetos caballeroi Pritchard, 1960 (new synonymy); Preptetos pritchardae Toman, 1989 nec Ahmad, 1984 (new synonymy). Pomacentrid material studied Parma polylepis Gtinther. Intestine. THC Nos 3324 (2), 3486 (1). QM GL 14778-9, BM(NH) 1992.19.5.7. Other material studied Naso annulatus (Quoy & Gaimard), Acanthuridae. Site? Collector: H.W. Manter. HWM No. A69a. Description

Measurements of 3 worms from P. polylepis and, following a comma, those from 2 flattened worms from N. annulatus, along with some descriptive details: Body 1,081-1,542 x 372-469 (Fig. 10), 1,5611,797 x 571-716. Granules of eye-spot pigment scattered in forebody. Gland-cells scattered throughout parenchyma. Oral sucker 80-92 × 84103, 97-111 x 96-109. Ventral sucker 95135 × 92-132, 110-177 x 134-193. Sucker-ratio 1:1.10-1.47, 1.40-1.77. Forebody 29-36, 2428% of body length. Prepharynx 32-64, 5-26. Pharynx 55-72 x 58-80, 71-80 x 44-55. Oesophagus 23-64, 35-61; 36-200, 135-1,220% of pre-

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pharynx length. Intestinal bifurcation 143-233, 174-203 from ventral sucker. Caeca reach to 95185, 109-148 from posterior extremity. Testes diagonal, either side of excretory vesicle: anterior 106-166 x 74-142, 151-232 x 145-177; posterior 126-184 × 79-122, 156-284 × 173-177. Post-testicular region 22-27, 22-24% of body-length. External seminal vesicle lacking associated glandcells. Cirrus-sac overall length 187-251,360-392; width 63-71, 93-122; reaches 92-148, 196-218 into hindbody. Genital pore sinistro-lateral to or antero-sinistral to ventral sucker. Ovary trilobed; 77-114 x 77-94, 109-132 x 100-133; 119-200, 235-245 from ventral sucker. Seminal receptacle globular; sinistro-dorsal to ovary. Laurer's canal opens dorsally close to sinistral margin of worm at about level of ovary. Eggs 68-84 x 34-42 (74 x 37), 75-97 x 41-51 (85 x 46). Vitellarium reaches 116-244, 39-80 into forebody. Excretory vesicle I-shaped; passes between testes, dextral to uterus, ovary and ventral sucker, dorsal to left caecum near intestinal bifurcation; terminates at about level of pharynx. Type-host and locality: Xesurus scalprum, Hamazima, Mie Prefecture, Japan. Records: 1. Yamaguti (1940); 2. Pritchard (1960); 3. Pritchard (1963); 4. Yamaguti (1970); 5. Dyer, Williams & Williams (1988), 6. Toman (1989); 7. Machida & Uchida (1990); 8. Present study. Descriptions: 1,2,3,4,7,8. Definitive hosts: Acanthuridae: Acanthurus bleekeri (5), Naso annulatus (4,8), N. brevirostris (3,4,6,7), N. hexacanthus (2,3,4,7), N. lituratus (7), N. tuberosus (7), N. unicornis (3,7), N. vlamingi (7), Xesurus scalprum (1). Labridae: Thalassoma duperreyi (3). Pomacentridae: Parma polylepis (8). Distribution: FAO Fisheries Area 51 Indian Ocean, W [Seychelles (6)], 61 Pacific, NW [Japan (1,5,7)], 7i Pacific W. Central [Queensland (8)], 77 Pacific, E Central [Hawaii (2,3,4)]. Discussion

We can detect no convincing differences between

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our specimens and any of the descriptions of P. xesuri or its synonyms. Pritchard (1960) differentiated her new species P. caballeroi from the 'similar' species P. xesuri, by its pointed posterior end and its long prepharynx. Later (Pritchard, 1963), she stated that the shape of P. caballeroi varied to include rounded ends. The range of prepharynx length given in published descriptions varies: 24-45 (Yamaguti, 1940), 40-127 (Pritchard, 1960), 20-120 (Yamaguti, 1970); and we have also found it to vary greatly, particularly when considered in relation to oesophagus length. The anterior extent of the vitellarium in Pritchard's (1960) figure appears to be a little posterior to that found by Yamaguti (1970). Yamaguti (1970) described the vitellarium of P. caballeroi as reaching a little anterior to the ventral sucker or opposite the anterior margin; the figure, however, shows a distribution identical to that of Yamaguti (1940) and our specimens. In fact, the figures in Yamaguti (1940) and (1970) are strikingly similar. Bearing in mind these considerations, and also the fact that most authors have distorted their material by flattening, we consider that P. xesuri and P. caballeroi are synonymous. Toman (1989) produced a key to the genus Preptetos and separated P. xesuri on an erroneous view of its vitelline distribution. He differentiated P. caballeroi and his P. pritchardae (pre-occupied by P. pritchardae Ahmad, 1984) by several features. The first feature he mentioned was the ventral sucker position, but he failed to note that Pritchard (1963) had said of P. caballeroi that the ventral sucker is 'sometimes about one-third body-length from the anterior end, sometimes nearer midbody'. He also considered the position of the uterus to the left of the ovary as a distinguishing feature, but we find considerable variation in this feature in only three worms from the pomacentrid. The number of eggs (few or numerous) was also mentioned, but Pritchard's quotations of 6-10 (1960) and 50-60 (1963) for P. caballeroi suggest that this is a dubious criterion. Other features, such as body-size (rarely a reliable character in digeneans) and sucker-ratio (with a large overlap), which were used by Toman as distinguishing features, are, we believe, not sufficient

to justify the belief that P. xesuri and P. pritchardae Toman, 1989 are distinct. It should also be noted that Machida & Uchida (1990) found considerable variation in sucker ratio and egg-size in P. caballeroi.

Preptetos cannoni Barker, Bray & Cribb, in press Material studied Pomacentrus bankanensis Bleeker. Site:? Collector: J. Beuret. THC No. 1567 (1). QM GL 14780. Description Measurements of single worm recovered are: Body 951 x 216. Oral sucker 71 x 85. Ventral sucker 92 x 88. Sucker ratio 1:1.04. Forebody 36% of body-length. Prepharynx 35. Pharynx 68 × 74. Oesophagus 32; 91% of prepharynx length. Intestinal bifurcation 124 from ventral sucker. Caeca reach to 124, 129 from posterior extremity. Testes: anterior 142 x 138; posterior 171 × 147. Post-testicular region 21% of bodylength. Cirrus-sac overall length 242; width 90; reaches 58 into hindbody. Genital pore sinistrolateral to ventral sucker. Ovary trilobed; 148 × 106; 23 from ventral sucker. Egg 74 × 45. Vitellarium reaches 190 into forebody and anterior to intestinal bifurcation. Comment This single worm appears to be identical to P. cannoni as described by Barker et al. (in press) from Siganus lineatus [Siganidae] from Heron Island.

Acknowledgements We thank Rob Adlard, Glenn Anderson, Helena Hall, Sylvie Pichelin, Desley Scott and Andrew Suttie of the University of Queensland, plus Vicki Sands of Queensland Museum, for assistance with the collection and preparation of the material de-

Lepocreadiids of pomacentrid fishes scribed in this paper. We are indebted to Jeff Johnson of the Queensland Museum for help with fish identification and to the Director and staff of the University of Queensland Heron Island Research Station for invaluable assistance in the field. We are grateful to Dr Jun Araki of the Meguro Parasitological Museum, Tokyo, Professor M.H. Pritchard of the Harold W. Manter Laboratory, Lincoln, Nebraska and Dr D. Hirst of the South Australian Museum, Adelaide for kindly lending us specimens. Dr T. Shimazu of the Nagano Prefectural College, Nagano, Japan, kindly allowed us to look at his specimens and gave information concerning Ozaki's collection. Dr D.I. Gibson of The Natural History Museum, London read the manuscript. The work was supported by a Queen Elizabeth II fellowship to THC, an ARC National Research Fellowship to SCB, an ARC grant A19031169 to THC & SCB, a University of Queensland Special Project Grant to SCB and a University of Queensland Travel Grant to RAB.

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