Geographic distribution features of subgenus and life forms of Lymnaeidae (Gastropoda,Pulmonata) in eastern Europe

The relative species variety as a ratio of the species number known from the territory north of the polar circle and the species number in eastern Europe as a whole has been calculated for subgenera and life forms of Lymnaeidae. The largest value of this feature is a specific parameter for ampla-like life forms. The domination of one life form is a result of its adaptation for both life in places with wave activity and water respiration. The relatively high species variety of the subgenera Lymnaea and Peregriana is related to domination of the ampla-like life form arranged by the mentioned taxons.