Eucotylidae is a family of microphalloid digeneans parasitising as adults in the urinary system of birds. There are few molecular data on members of this family, and phylogenetic relationships of its genera and species are still unclear. Here we present new morphological and molecular data on a eucotylid species Tanaisia atra (Nezlobinsky, 1926). Specimens of T. atra were found in Eurasian Coot Fulica atra Linnaeus, 1758 in European and Asian parts of Russia and examined using optical and SEM microscopy and molecular techniques. We report the presence of a well-developed cirrus sac and different types of tegumental scales in this species for the first time. All molecular markers used in our study (ITS2 region, 28S rRNA and cox1gene) indicate that T. atra isolates from European and Asian parts of Russia are conspecific. In phylograms based on ITS2 region and 28S rRNA gene sequences, T. atra clustered with other Tanaisia spp.