Issues of species identification within Paramphistomoidea Fischoeder, 1911 (Trematoda).

Cercariae of three Paramphistomoidea species were identified in the trematode fauna parasitizing the freshwater snails Gabbia fuchsiana from Vietnam and Helicorbis sujfunensis and Gyraulus centrifugops from the southern part of the Russian Far East. To elucidate their taxonomic status, the study included a morphological description accompanied by a molecular analysis using both nuclear and mitochondrial markers. An analysis of the evidence obtained showed that taxonomic identification of paramphistomes can only be possible on the basis of both morphological and molecular data, which are not always available for most representatives of the superfamily Paramphistomoidea. Therefore, genera could be identified for only two trematode species considered in this study. The issue of incorrect taxonomic identification of some trematodes from this superfamily was also highlighted. Due to the challenges encountered in the practical application of the previously obtained sequences to the development of diagnostic PCRs, the superfamily Paramphistomoidea requires careful taxonomic revision.