The taxonomic position and phylogenetic relationships of two steppe species of Lymnaeidae, Lymnaea taurica (Clessin 1880) and L. kazakensis Mozley 1934, have been studied by means of classical morphological and molecular genetic methods. The topotypes of Limnaea taurica Clessin 1880 have been examined and the neotype of this species has been designated. Molecular data shows that L. kazakensis distributed in the southern parts of the Urals and Western Siberia is conspecific with L. taurica known from southern regions of the Ukraine and European Russia. However, given their strong geographical isolation (ranges are not overlapping), we regard L. kazakensis as a Siberian subspecies of L. taurica. Phylogenetically, L. taurica comb. n. is much closer to the Eurasian species of the genus Lymnaea Lamarck 1799 (type species Helix stagnalis Linnaeus 1758) than to species belonging to the genera Corvusiana Servain 1881 (type species Helix corvus Gmelin 1791) and Stagnicola Leach in Jeffreys 1831 (type species Buccinum palustre O. F. Müller 1774). L. taurica should be placed in the genus Lymnaea rather than in Corvusiana as was done by previous authors (Lazareva 1967; Kruglov, Starobogatov 1984, 1993). The splitting of the genus Lymnaea into two subgenera: Lymnaea s.str. and Kazakhlymnaea Kruglov & Starobogatov 1984 (type species Lymnaea palustris kazakensis Mozley 1934) is proposed.