Molecular and morphological evidence for close phylogenetic affinities of the genera Macrodera, Leptophallus, Metaleptophallus and Paralepoderma (Digenea, Plagiorchiata)

Genera Paralepoderma, Leptophallus and Metaleptophallus have traditionally been classified as a group of closely related genera considered by most aut hors as members of the subfamily Leptophallinae, family Plagiorchiidae (Dig enea, Plagiorchiata). At the same rime the systematic position of the genus Macrodera was for a long time unstable and its phylogenetic affinities con troversial. Different authors allocated this genus in the family Ochetosoma tidae or as a type genus of separate family Macroderidae. The former three genera include parasites of snake digestive tract and the last one - parasi tes of snake lung. Some morphological features of adult and larval stages i ndicated, however, their possible close affinity. Molecular analysis based on the partial sequences of the 28S ribosomal DNA gene has demonstrated ver y close phylogenetic relationships between these four genera. The molecular data are supported by morphological characters of adult stages (first of a ll, presence of external seminal vesicles in all four genera), peculiaritie s of life cycle and chaetotaxy of cercariae. A hypothesis of the probable w ays of speciation in this group is proposed.