Parasites of South Pacific Fishes: Ii. Diplectanum Melanesiensis N. Sp., a Monogenetic Trematode From Fiji and the New Hebrides

Abstract

Thirty-six immature examples of the serranid Epinephelus 71ierrc~ Bloch were collected from coral pools a t Aneityum (New Hebrides) and Maliuluva Islet (Fiji), on four occasions from 1952 to 1951. The gills of all of them were infected \\,it11 Diplectnwr~rt~ 71zelnnesie~~sis 11. sp., the closest Icnown relatives of which parasitize allied hosts in Japan (D. epirtepheli Yanlaguti) and Celebes (D. serrar~i Yamaguti). The South Pacific species resembles D. serrnni but differs from D. epinephe!i in lacking a conspicuous ejaculatory bulb and in having a transversely positioned ovary thc elongate terminal portion of which enfolds thc right caecum. I t is distinguisherl from both these species by its markedly s~iialler size (217 to 500 p by 66 to 117 p , a v . , 366 by 92 p) and the structure of the squamodiscs, \vhich ha1.c nine concentric ro\\-s of rodlets, the four innermost ones forming complete circlets. Can. J. 2001. 36 (19.58) Can. J. Zool. Downloaded from www.nrcresearchpress.com by DUKE UNIV BOX 90187 on 10/01/12For personal use only. *Termination of specific name enlended by Sproston (6). Originally Lepidoles fluvialilzcs Johnston and Tiegs, then Dipleclanzrnzflzr.~ialzlis (J. and T.) Pr~ce.

Resolution of the discrepant host-specificity of Pseudorhabdosynochus species (Monogenea, Diplectanidae) from serranid fishes in the tropical Indo-Pacific

“…The absence of this monogenean species in 5 specimens from Wallis Island contrasts with the high prevalences of this species reported from Vanuatu (100%, Laird 1958) and New Caledonia (97%, Hinsinger and Justine 2006b). This suggests that this monogenean is absent in this part of the Pacific Ocean, but more dissections would be needed.…”

“…Justine (2005a) redescribed the species from E. merra off New Caledonia. Laird (1958) and Hinsinger and Justine (2005b) reported prevalences of 100% and 97% in Vanuatu and New Caledonia, respectively. At this stage, two facts were apparent: (a) P. cupatus had two hosts, E. merra and E. fasciatus, and (b) E. merra had a monogenean fauna which changed drastically according to locality, with P. cupatus and P. vagampullum in Australia vs P. melanesiensis in Vanuatu, Fiji and New Caledonia. These two facts appeared outstanding: (a) the relatively wide specificity of P. cupatus contrasted with the numerous observations by Justine (2005aJustine ( , b, 2007Justine ( , 2008Justine ( , 2009) on the Pseudorhabdosynochus fauna of New Caledonia, showing that species of this genus were generally strictly specific, with a single host; and (b) the drastic change of monogenean fauna in a species of marine fish according to the locality had apparently no equivalent in the literature.…”

“…P. vagampullum was not found in any of the numerous diplectanid specimens from E. merra from New Caledonia (Justine 2005a, Hinsinger andJustine 2006b). Zeng and Yang (2007) examined monogeneans from E. quoyanus from the South China Sea and found two species of the cupatus group, which they did not describe, and in addition reported P. vagampullum, P. lantauensis Beverley-Burton et Suriano, 1981 andDiplectanum grouperi Bu, Leong, Wong, Woo et Foo, 1999, and a new species, P. justinei Zeng et Yang, 2007. Pseudorhabdosynochus melanesiensis (Laird, 1958) Kritsky et Beverley-Burton, 1986 was described from E. merra off Vanuatu and Fiji. Justine (2005a) redescribed the species from E. merra off New Caledonia.…”

“…In contrast, E. merra in New Caledonia harbours only P. melanesiensis (Laird, 1958). It is concluded that the type-host of P. cupatus and P. vagampullum is not E. merra, as indicated in Young (1969), but E. quoyanus, and that P. cupatus sensu Young comprises two species, P. cupatus from E. quoyanus and P. youngi sp.…”

“…Pseudorhabdosynochus cupatus was originally described from Epinephelus merra Bloch (type-host) and E. fasciatus Forsskål (other host). In E. merra in New Caledonia, Justine (2005a) and Hinsinger and Justine (2006b) did not find P. cupatus but found abundant P. melanesiensis (Laird, 1958) Kritsky et Beverley-Burton, 1986, a species originally described from this fish species in Vanuatu and Fiji (Laird 1958); in E. fasciatus in New Caledonia they found a diplectanid that they considered conspecific with P. cupatus. Pseudorhabdosynochus vagampullum, also described from E. merra, was never found in New Caledonia (Justine 2005a, Hinsinger andJustine 2006b).…”