Vermipharyngiella Unica gen. et sp. n. (Plathelminthes, Tricladida, Paludicola), a new planarian genus and species from lake Baikal with peculiar pharyngeal structure

Abstract

An illustrated description of a new monotypical genus of endemic Baikal planarians, Vermipharyngiella gen. et sp. n., is provided. The representatives of the new genus differ from those of all other known freshwater planarian genera by a very unusual structure of the pharynx. There are three well-separated, compactly arranged muscular layers in the wall of the pharyngeal canal: subepithelial circular, medial longitudinal and inner circular. Such arrangement of the muscular layers has not been found in any of four freshwater triclad families known. The problem of the attribution of the new genus to one of these families is discussed.