Shells of L . stagnalis s. l. from the studied areas (A-D) and the scheme of shell measurement (E). (A) Buldyr Channel in the floodplain of the Irtysh River, Omsk Region, Russia. (B) A lake in Tobolsk town, Tyumen Region, Russia. (C) Tenis Lake, Omsk Region, Russia. (D) A lake (oxbow) in the floodplain of the Nura River near Korgalzhyn Settlement, Akmola Region, Kazakhstan. (A, B) belong to the fragilis morphotype. (C, D) belong to the stagnalis morphotype. Scale bars, 5 mm.