Freshwater Planarians (Platyhelminthes: Tricladida: Planariidae) from the Kuril Islands and Kamchatka

Collections of freshwater planarians made by two expeditions to the Kuril Islands and Kamchatka are described, thus providing the first comprehensive account of the occurrence of this group of animals in the Kuril Archipelago. The samples contained three species: Seidlia schmidti (Zabusov, 1916), S. elongata (Zabosova, 1929), and Phagocata sp. The new records for S. schmidti and S. elongata include asexual specimens that were identified on the basis of their eye arrangement. This study shows that freshwater planarian species that were already known to occur in Kamchatka and Japan have also colonized the Kuril Islands. Possible scenarios for dispersal into the Kuril Islands from two mainland source areas during the Last Glacial Maximum are discussed.