FIRST RECORDS OF THE NORTH AMERICAN GASTROPOD <i>PHYSELLA ACUTA</i> (DRAPARNAUD, 1805) IN THE KUYBYSHEV WATER RESERVOIR, RUSSIA
The gastropod Physella acuta (Draparnaud, 1805) has been recorded for the first time on shallow shore areas in the Volga Reach of Kuybyshev Water Reservoir, Russia during a sampling in 1998, and for the second time in the same Volga Reach in 2009. The way of its invasion is still unknown. Possibly, this gastropod was introduced from aquariums, and less possibly migrated from the lower reaches of the Volga River.