Phylogeny and morphology of some European cyathocotylid digeneans (Trematoda: Diplostomoidea).

Abstract

The Cyathocotylidae Mühling, 1898 is a family of primitive diplostomoid trematodes important for understanding the evolution of the superfamily Diplostomoidea. However, cyathocotylids remain poorly studied with the use of molecular techniques. In this study we sequenced the 5.8S + ITS2 region,, andgenes of two cyathocotylid species and obtained new morphological data on them. We proposenom. nov. instead of the preoccupied nameSzidat, 1936 (junior homonym ofStremme, 1911). Adults ofcf.(Ishii, 1935) andKatsurada, 1914 were collected from fish-eating birds in the south of the European part of Russia.cf.was very similar tobut differed from it in the shape of the testes. Thegene dataset provided the best-resolved phylogeny of the Cyathocotylidae to date. In the phylogram based on partial sequences of this gene,was close to members ofDubois, 1983,Chandler & Rausch, 1947 andSzidat, 1936.cf.clustered with members ofMühling, 1896 andSzidat, 1936. Phylogenetic analysis based on the 5.8S + ITS2 dataset showed that adults ofexamined in our study were conspecific with the metacercariae from the musculature of fish collected in Hungary and Italy. It also revealed probable misidentifications of larvae and adults of cyathocotylids whose sequences are deposited in GenBank NCBI.