Class Oligochaeta Grube, 1850 - oligochaetes see [unranked] oligochaetous Clitellata Subclass Diplotesticulata Superorder Metagynophora Jamieson, 1988 Order Opisthopora Suborder Crassiclitellata Cohort Aquamegadrili Jamieson, 1988 Superfamily Biwadriloidea Jamieson, 1971 Family Biwadrilidae Jamieson, 1971