Kingdom Animalia Linnaeus, 1758 - animals
   Phylum Nematoda Gegenbaur, 1859 - round worms
     Class Enoplea Inglis, 1983
       Subclass Enoplia Pearse, 1942
         Superorder Enoplica Hodda, 2007
           Order Trefusiida Lorenzen, 1981
             Suborder Trefusiina Siddiqi, 1983
               Superfamily Trefusioidea Gerlach, 1966
                 Family Xenellidae De Coninck, 1965 see Family Xennellidae De Coninck, 1965