JKAU: Mar. Sci., Vol. 22, No. 1, pp: 3-13 (2011 A.D. / 1432 A.H.) DOI : 10.4197/Mar. 22-1.1 Hypocreadium cavum (Digenea: Lepocreadiidae: Hypocreadium) in Marine Fishes, Abalistes stellaris (Balistidae) From the Red Sea, Coast of Yemen. Ali B. Al-Zubaidy Department of Marine Biology and Fisheries, Faculty of Marine Science and Environment, Hodeidah University, Yemen Abstract. Specimens of the marine fish, Abalistes stellaris (Balistidae) were collected from local fish market in Hodeidah during the period between September 2008 and July 2010 . Six out of 80 (7.5%) of these fish were found to harbour intestinal trematodes, Hypocreadium cavum Bray and Cribb, 1996 (Lepocreadiidae). Since there is no previous report on these digenetic trematode from any fish host in Yemen, the present recording may well be considered the first in this country. Introduction Members of the Lepocreadiidae Odhner, 1905 have a cosmopolitan distribution as intestinal parasites of marine teleosts (Bartoli and Bray, 2004). They are recognizable as worms with widely distributed Vitelline folices, a spinous tegument, a cirrus-sac, usually with a distinct external seminal vesicle and a typically I-shaped excretory vesicle (Bray, 2005). Ozaki (1936) erected the genus Hypocreadium to include H.symmetrorchis in Monocanthus cirrhifer from Japan. Manter (1940), Arai (1962) and Nahhas and Cable (1964) concluded that Hypocreadium Ozaki,1936 should be considered as a synonym to Pseudocreadium Layman,1930. However, Yamaguti (1971) refused these conclusions and preferred to retain the genus Hypocreadium Ozaki, 1936 as a separate 3 4 Ali B. Al-Zubaidy genus which could be easily separated from other related genera according to the position of genital pore, ovary and prostate cells as well as the extension of the excretory vesicle. Bray and Cribb (1996) revised the genus, recognizing 13 species: Hypocreadium symmetrorchis (type- species); H. balistes; H. biminensis; H. cavum; H. galapagoensis; H. grandisquamis; H. indicum; H. lactophrysi ; H. lamelliforme; H. myohelicatum; H. patellare; H. scaphosomum and H. spinosum. Bray et al. (2009) recognized 15 species, including H. toombo Bray and Justine, 2006 and H. picasso Bray et al.2009. Balistid fish, Abalistes stellaris (Bloch and Schneider,1801) is a fish belonging to family Balistidae, with distribution in Indo-west Pacific, Red Sea and east Africa to southeast Asia, north to Japan and south to northern Australia, eastern Atlantic. It inhabits coastal areas, usually found over muddy and sandy bottoms, also around reefs together with the sponges and algae. It is feeding on benthic animals (Figueiredo and Menezes, 2000). The parasite fauna of this fish species from the Red Sea, Yemen coast, is poorly known. During investigations into helminths parasites of fish, A. stellaris, specimens of Hypocreadium Ozaki, 1936 were collected and identified as H. cavum Bray and Cribb, 1996 which represents the first record of this genus in Yemen Coastal water on the Red Sea. Materials and Methods During September 2008 to July 2010, 80 specimens of the fish Abalistes stellaris (Balistidae) were collected from the local fish market in Hodeidah, Yemen. Standard parasitological techniques were used to examine the alimentary canal of the fish. Digenean collected from freshly killed fish were fixed by being pipetted into nearly boiling saline and immediately preserved in 5% formalin or 70% ethanol. Whole-mounts were stained in acetocarmine, cleared in Lacto phenol and mounted in Canada balsam. Measurements are quoted as the range with the mean in parentheses. The specimens are deposited in the laboratory of Marine Biology and Fisheries Department, Faculty of Marine Science and Environment, Hodeidah University, Hodeidah, Yemen. Trematode was identified to species level based on the keys of Bray and Cribb (1996); Bray et al.(2009) and with the help of Prof. Dr. R.A. Bray. Hypocreadium cavum (Digenia: Lepocreadiidae: Hypocreadium)… 5 Results and Discussion Classification Class: Trematoda Rudolphi, 1808 Subclass: Digenea Carus, 1863 Family : Lepocreadiidae Odhner, 1905 Subfamily: Lepocreadiinae, Odhner, 1905 Synonym: Dermadenidae, Yamaguti, 1958 Genus: Hypocreadium Ozaki, 1936 Diagnosis: Body broadly oval, rounded or slightly wider than long; flattened. Tegumental spines sparse or apparently absent. Oral sucker sub terminal, sub globular. Ventral sucker rounded to oval and in the middle of body. Prepharynx present or apparently absent. Pharynx oval. Oesophagus usually distinct. Intestinal bifurcation in mid-forebody. Caeca undulating in arc around gonads, terminate blindly near median line posterior to ovary. Testes symmetrical in anterior hind body. External seminal vesicle saccular to elongate. Cirrus-sac large, claviform. Internal seminal vesicle sub globular. Pars prostatica vesicular; bipartite or elongate curved. Ejaculatory duct long and wide. Genital atrium distinct. Genital pore sinistral at various levels in forebody. Ovary inter- testicular; oval, weakly lobed or entire. Canalicular seminal receptacle and Lauer’s canal present. Uterus pre-ovarian, may also pass posteriorly to ovary. Eggs tanned, operculate. Vitelline follicular; fields around gonads with distinct wide border lacking follicles. Excretory pore dorsal just posterior to ovary or testes; vesicle wide, reaches to gonads, two arms reach into forebody. In marine teleost, mainly Tetraodontiforms. Type species H. symmetrorchis Ozaki,1936. H. symmetrorchis is unfortunately, atypical for the genus, in that it is broadly oval, rather than rounded as is the case for most species. Also, unfortunately, the excretory system was not described, but the similar species H. biminensis is described with the excretory pore dorsal at about the posterior margin of the testes (Bray and Cribb, 1996). Hypocreadium cavum Bray and Cribb, 1996 ( Fig. 1). Description (base on 3specimens) and Measurements (µm): Body: rounded,1.350-2.550 mm (2.08) in length,1.320-2.640 mm (2.100) wide at its middle. Pre oral lobe: 16- 40 ( 31). Spines: No tegumental spines seen. 6 Ali B. Al-Zubaidy Oral sucker: sub terminal, round, 105-149×118-160(119-143). Ventral sucker: rounded, 145- 237×152-225 (131×159). Sucker ratio: 1:1.07-1.28 (1.15). Pharynx: Oval, 75-114×75-131(101×124). Oesophagus: distinct,79-160 (121) . Forebody: 620-1.080(851) in length, representing 37-39% of total body length. Intestinal bifurcation in mid-forebody. Testes: 2, entire, oval, symmetrical,135-320×156-288(254×210). External seminal vesicle: saccular, at level of ventral sucker, 120- 280×65-112(178×83). Internal seminal vesicle: oval. Cirrus-sac: large, claviform,337-510×156-230 (401×206). Ejaculatory duct: muscular, long, folded. Genital atrium distinct. Genital pore sinistral at level of anterior part of oesophagus. Ovary: more or less oval, 108-182×119-177(143×156).Oviduct passes anteriorly from ovary. Eggs: few, operculate. Lauer’s canal opens dorsally to ovary, sinistral testis or between. Uterus anteriorly to ovary. Excretory pore: dorsal, median. Fig. 1. Hypocreadium cavum from Abalistes stellaris, ventral view. Scale bar = 0.5mm. os = oral sucker. Ph = pharynx. gp = genital pore. cs = cirrus sac. vs = ventral sucker. t = testes. ov = ovary. oe = oesophagus. Hypocreadium cavum (Digenia: Lepocreadiidae: Hypocreadium)… 7 Taxonomic Summary: Synonyms: Pseudocreadium scaphosomum Menter,1940 of Parukhin and Chikunova (1964); Pseudocreadium patellarae (sic) (Yamaguti, 1938) of Oshmarin (1965); Hypocreadium indicum (Madhavis, 1972) of Hussain et al., (1986). Host: Abalistes stellaris, Balistidae, Starry triggerfish. Locality: Red Sea, Hodeidah- Yemen coastal water. Site of infection: Intestine. Prevalence: 6/80 fishes examined; 7.5%. Intensity of infection: 1 parasite per each fish infected. Discussion Prior to 2004, more than 30 subfamilies were described under the Lepocreadiidae Odhner, 1905. More recently, Bray (2005) has comprehensively reviewed this family, accepting the validity of only three subfamilies, the Lepocreadiinae Odhner, 1905; Lepidapedinae Yamaguti, 1958 and Aephnidiogeninae Yamaguti, 1934, based on essential differences in the structure of the male terminal genitalia. He accepted 60 genera as valid within the Lepocreadiinae. One of these is Hypocreadium Ozaki, 1936. It constitutes a group of poorly-known species, characterized by their flattened, broadly oval to circular outline and parasitism in tetradontid hosts. Another diagnostic character is the dorsally situated excretory pore, usually well anterior to the posterior extremity, between the caecal extremities. According to Bray and Cribb (1996) 13 species were recognized Hypocreadium cavum was one of them. Bray and Justine (2006) described H. toombo n. sp. from Abalistes stellatus and Rhinecanthus sp. (Balistidae) in New Caledonia. Bray et al., (2009) redscribed 3 species of the genus Hypocreadium: Hypocreadium cavum; Hypocreadium patellare, and Hypocreadium picasso n. sp. from some species of triggerfish from different locality (Abalistes stellatus; Balistoides viridescens and Rhinecanthus aculeatus, R. verrucosus and Pseudobalistes fusc respectively). These species are found in the warmer waters of the western Atlantic Ocean and across the Indian and Pacific Ocean. The life cycle is unknown (Bray and Cribb, 1996). In this study, Hypocreadium cavum Bray and Cribb, 1996 was found in Abalistes stellaris, Balistidae, starry triggerfish. According to Bray et al. (2009) the great preponderance of records of the genus is from 8 Ali B. Al-Zubaidy fishes of the tetraodontiforms