Diversity of long-tail Echinochasmus spp. (Trematoda: Echinostomatidae) in Northeast Asia: cryptic species revealed by genetic data

Abstract In this study, 41 individuals of long-tailed cercariae of the genus Echinochasmus parasitizing the freshwater snails Koreoleptoxis spp. were collected in different localities of the southern part of the Russian Far East. Partial nucleotide sequences of the mitochondrial cox1 gene were generated and analysed for all the specimens obtained. Phylogenetic relationships within the family Echinochasmidae were assessed using all available published data. Bayesian inference and maximum likelihood analyses revealed six morphologically similar species or species-level genetic lineages of Echinochasmus circulating in the Russian Far East and on the islands of Japan. Of these, two represent previously described valid species, E. milvi and E. suifunensis.