Electrophoretic and morphological differentiation of three sympatric species of the genus Lecithochirium (Trematoda: Hemiuridae), parasites of marine fishes.

Three sympatric species of the genus Lecithochirium, Lecithochirium fusiforme, Lecithochirium rufoviride and Lecithochirium musculus, parasites of Conger conger and Anguilla anguilla, were compared morphologically and electrophoretically. The three species can be discriminated by enzyme analysis, and differentiation can also be made by the analysis of several morphometric features, in particular body size and sucker ratio. Fourteen enzyme systems representing 15 loci were examined by starch gel electrophoresis. Two of the enzyme systems studied (ALD and GOT) were totally diagnostic among Lecithochirium species. Fixed allelic differences between L. fusiforme and L. musculuswere observed at five loci, between L. fusiforme and L. rufoviride at nine loci, and between L. musculusand L. rufoviride at ten loci. The percentage of fixed differences among the species under study ranged from 33 to 77%. The results show that the three taxa can be clearly differentiated, and that L. fusiforme is genetically more similar to L. musculus than to L. rufoviride.