Bivalves and the Bucephalidae: A parasitic system on the Great Barrier Reef

Bott, Nathan James (2006). Bivalves and the Bucephalidae: A parasitic system on the Great Barrier Reef PhD Thesis, School of Molecular and Microbial Sciences, The University of Queensland.

       
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Author Bott, Nathan James
Thesis Title Bivalves and the Bucephalidae: A parasitic system on the Great Barrier Reef
School, Centre or Institute School of Molecular and Microbial Sciences
Institution The University of Queensland
Publication date 2006
Thesis type PhD Thesis
Supervisor Thomas Cribb
Total pages 206
Collection year 2006
Language eng
Subjects L
300508 Parasitology
780105 Biological sciences
Abstract/Summary This study set out to examine, for the first time, both the molluscan intermediate and the teleost definitive hosts of a major assemblage of trematode parasites present on the Great Barrier Reef (GBR). The parasite taxon was the Bucephalidae which occur in piscivorous fishes as sexually reproducing adults and in bivalves as asexually reproducing stages. The goal was to characterise the overall richness of the system and to explore patterns of host-specificity. Because of the size of this fauna it was not possible to incorporate all the taxa found in this study. This thesis reports the results of a survey of bivalves from this region, taxonomic studies on several elements of the fauna of fishes, and efforts to link life-cycles between bivalves and fishes. I surveyed 2256 bivalve individuals (47 species, 17 families) from South-east Queensland, Heron Island (southern GBR) and Lizard Island (northern GBR). Infections of trematode species from three families, Bucephalidae, Gorgoderidae and Monorchiidae, were found. Overall prevalence of infection was 2.3%. The Bucephalidae (11 species) was the most commonly found family. A single gorgoderid infection was found from a venerid, Lioconcha castrensis. This is the first report of a gorgoderid from a marine bivalve and phylogenetic analysis suggests that the species belongs to the Gorgoderinae. Monorchiids (5 species) were found from Tellinidae and Lucinidae. All infections are new host/parasite records. I deduce that this study produced lifecycle information, but no actual identifications, for 10% of the species of trematodes that infect bivalves of Queensland marine waters. Prosorhynchoides apogonis n. sp. is described from the intestine of the apogonid Cheilodipterus macrodon from the southern GBR. This is the first bucephalid to be described from the teleost family Apogonidae. Prosorhynchoides lamprelli n. sp. is described from the intestine of the carangid Caranx papuensis from off Lizard Island, GBR. This is the first bucephalid to be described from Caranx papuensis. A new trematode genus, Grammatorcynicola n. g. (Dolichoenterinae), and two new species, G. brayi n. sp. and G. nolani n. sp., are described from the intestines of the scombrids, Grammatorcynus bicarinatus and Gr. bilineatus respectively. Grammatorcynicola n. g. differs from other dolichoenterine genera in having a simple sucker-like rhynchus, the ovary anterior to the testes and by not having a particularly thick cirrus-sac wall. Six new species of bucephalid trematodes from the prosorhynchine bucephalid genera Prosorhynchus Odhner, 1905 and Neidhartia Nagaty, 1937 are reported from the epinepheline serranid genera Cephalopholis, Cromileptes, Epinephelus and Variola from the GBR. Two species of Prosorhynchus and one Neidhartia are reported from Epinephelus spp., P. jexi n. sp. from E. quoyanus, P. lafii n. sp. from E. fuscoguttatus, and N. epinepheli n. sp. from E. maculatus. The other species are P. robertsthomsoni n. sp. from several species of Cephalopholis, P. conorjonesi n. sp. from Cromileptes altivelis, and P. milleri n. sp. from Variola louti. I examined three species of Plectropomus (Serranidae: Epinephelinae), Pl. laevis, Pl. leopardus and Pl. maculatus from off Heron Island and Lizard Island on the GBR. Nine bucephalid species from the Prosorhynchinae were found, three species of Neidhartia and six species of Prosorhynchus. The three species of Neidhartia, N. haywardi n. sp., N. plectropomi n. sp. and N. tyleri n. sp., are readily distinguishable by morphology. Two of the six species of Prosorhynchus (P. lesteri n. sp. and P. wrightae n. sp.) are easily distinguished from their other congeners by morphology but the other four species (P. adlardi n. sp., P. heronensis n. sp., P. munozae n. sp. and P. plectropomi n. sp.) are highly similar in morphology and were only distinguished convincingly by comparing their ITS2 rDNA sequences. Both P. adlardi n. sp. and P. wrightae n. sp. have also been found once in V. louti at Lizard Island. This is also the first study to identify life-cycle matches of the Bucephalidae using molecular techniques. I found two perfect life-cycle matches (identical sequences). The bivalve host of Prosorhynchoides lamprelli is a tellinid, Exotica clathrata; Rhipidocotyle sp. from the sphyraenid Sphyraena jello also has E. clathrata as its first intermediate host. Bayesian Inference Analysis shows that all seven species from bivalves that were sequenced belong to the Bucephalinae. Perhaps the most striking finding of the study was that one bivalve species, E. clathrata, was shown to harbour four separate species. Matching of ITS2 rDNA sequences between life-cycle stages is highly effective in circumstances of great richness such as the Great Barrier Reef. Based on my data collected, the total bucephalid species in the system is estimated to be 84.

 
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