Taxonomic redescription of Phagocata sibirica and comparison with Phagocata vivida (Tricladida, Paludicola)

Insufficient knowledge on the morphology and anatomy of the planarian flatworm Phagocata sibirica (Zabusov, 1903) has hampered adequate comparisons between species of Phagocata from the Far East and the assessment of biodiversity in this group of species. On the basis of an old sample of specimens, collected near the type locality in the vicinity of Lake Baikal by Russian workers who earlier had made important contributions to our knowledge on this group of flatworms, a redescription of the species is provided. The study of these specimens, together with information published by Russian workers, contributes to a much more detailed and comprehensive knowledge on the anatomy of Ph. sibirica. Furthermore, this new evaluation points to the fact that there is only one character in which the species Phagocatafontinalis (Zabusov, 1903) differs from Ph. sibirica. Previously, the species Phagocata vivida was sometimes considered to be conspecific with Ph. sibirica. On the basis of the examination of new material of Ph. vivida (Ijima & Kaburaki 1916), collected from a new Siberian locality, together with information from the literature, it is concluded that Ph. sibirica and Ph. vivida cannot be considered as conspecific.