Revision of Indian Bipaliid species with description of a new species, Bipalium bengalensis from West Bengal, India (Platyhelminthes: Tricladida: Terricola)

A new species of Bipaliid land planarian, Bipalium bengalensis is described from Suri, West Bengal, India. The species is jet black in colour without any band or line but with a thin indistinct mid-dorsal groove. Semilunar head margin is pinkish in live condition with numerous eyes on its margin. Body length (BL) ranged from 19.00 to 45.00mm and width varied from 9.59 to 13.16% BL. Position of mouth and gonopore from anterior end ranged from 51.47 to 60.00% BL and 67.40 to 75.00 % BL respectively. Comparisons were made with its Indian as well as Bengal congeners. Salient features, distribution and biometric data of all the 29 species of Indian Bipaliid land planarians are revised thoroughly. Genus controversy in Bipaliid taxonomy is critically discussed and a proposal of only two genera Bipalium and Humbertium is suggested.