Redescription of Japanese Bdellocephala annandalei from Lake Biwa-ko with comparative redescription of the Far Eastern and Kamchatkan Bdellocephala species (Tricladida, Paludicola)

Bdellocephala annandalei Ijima et Kaburaki, 1916, is an endemic planarian of Lake Biwa-ko in Central Japan. This lake-dwelling species inhabits the muddy bottom of the northern basin of the lake (20-103 m in depth). The species is characterized by its comparatively large size, uniformly light brown coloration, two small eyes, and a subterminal, ventral adhesive organ on the frontal end. A detailed taxonomic redescription of B. annandalei is given here and compared with the other three Far Eastern and Kamchatkan Bdellocephala species inhabiting epigean waters.