Molecular Diversity of Far-Eastern Trematodes of the Genus Crepidsotomum (Allocreadiidae) by Means of Nuclear 28S rRNA and Mitochondrial COI Gene Sequences

The ribosomal 28S rRNA and mitochondrial cytochrome oxidase subunit I (COI) gene fragments variation of several Crepidostomum species, collected from different fish species in Japan and south of Russian Far East, was estimated. On the basis of these data, taxonomical and population genetic structure conclusions for these trematodes were studied. Results of the analysis of the COI gene-based median-joining network indicate the presence of at least five groups of haplotypes that can be distinguished on the basis of definitive host-specificity. Genetic differentiation between these groups has been estimated. Occurrence of C. metoecus and C. farionis and the presence of at least one new Crepidostomum species in Japanese parasite fauna have been confirmed. Ribosomal 28S rDNA-based median-joining analysis indicates low diversity of several Crepidostomum species, reported in latest studies. Critical comments about the evidence of validity of the genus Stephanophiala and species Crepidostomum nemachilus were provided.