Two trematode species, Pseudoparabascus khotenovskii comb. n. and Acanthatrium ovatum (Trematoda: Microphalloidea), from East Asia: morphological and molecular data.

In this report, morphological and molecular characteristics are provided for two members of the subfamily Microphalloidea distributed in the south of the Russian Far East. Some of trematode specimens found in larvae of mayflies, stoneflies, and caddisflies and then experimentally reared to the adult stage in hamsters, according to their morphological features, belong to the species Acanthatrium ovatum previously recorded from Japanese bats. Molecular data has confirmed their membership in the family Lecithodendriidae and similarity to trematodes identified as Lecithodendriidae sp. F from Japan. The other specimens, experimentally reared in chickens, according to their morphological characteristics, meet the diagnostic criteria of the genus Parabascus. However, this species is not clustered with representatives of this taxon in the phylogenetic reconstruction based on 28S rRNA gene data. A molecular analysis has shown that it forms a single cluster with Pachypsolus irroratus and is a member of the family Pachypsolidae. It is here placed in the new genus Pseudoparabascus n. g. under the name Pseudoparabascus khotenovskii comb. n. The phylogenetic reconstructions based on two other markers, the cox1 mtDNA gene and the ITS2 rDNA region, have confirmed the assignment of these specimens obtained in both experiments to the above-considered taxonomic groups.