A NEW SPECIES OF INSULODRILUS (OLIGOCHAETA, PHREODRILIDAE) FROM LAKE-TANGANYIKA (EAST-AFRICA) WITH NOTES ON THE OLIGOCHAETE FAUNA OF THE LAKE

Insulodrilus genitalisetifera n. sp. is the second species of the genus Insulodrilus described from Lake Tanganyika (East Africa). It differs from other Insulodrilus in that it has genital chactae on the pregenital segment XI, probably homologues to the spermathecal chaetae on segment XIII. These extra genital chaetae are mentioned for the first time in the family Phreodrilidae. The current knowledge of the oligochaete fauna of Lake Tanganyika is discussed in the context of its old age, the suitability of its environment for oligochaetes, and the endemicity of its fauna. The Tanganyikan oligochaete fauna is limited to only 8 species, but this may be due to lack of studies.