Biwadrilidae Jamieson, 1971

This monogeneric family includes only one species, Biwadrilus bathybates (Stephenson), known only from the Lake Biwa region in Japan. It was originally described as a Criodrilus species, and Blakemore (2008b) transferred it back to Criodrilidae based on new material and re-analysis of previously observed material. However, molecular analysis shows this family solidly placed as the sister family to Kynotidae, and therefore quite distant phylogenetically from the Criodrilidae (James & Davidson 2012), hence we maintain it within Biwadrilidae, following Jamieson (1971, 1988).