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
               1 Family Biwadrilidae Jamieson, 1971