First finding of Baikalian amphipod Micruropus possolskii Sowinsky, 1915 (Amphipoda, Crustacea) in Lake Ladoga.
For the first time, the Baikalian amphipod species Micruropus possolskii Sowinsky, 1915 was recorded in the Shchuchiy Bay of Lake Ladoga in August 2012. The species was probably accidentally introduced into lakes of the Karelian Isthmus during intentional introduction of the another Baikalian amphipod species Gmelinoides fasciatus (Stebbing, 1899). Later M. possolskii penetrated into Lake Ladoga via different waterways connecting the lakes. The period of M. possolskii penetration into the lake is unknown. It is suggested that the species can spread in the littoral of Lake Ladoga, but mass development of the species is hardly probable.