Phylum Nematoda Gegenbaur, 1859 - round worms
   Class Secernentea Von Linstow, 1905
     Subclass Tylenchia (Thorne, 1949) Inglis, 1983
       Order Tylenchida G. Thorne, 1949
         Suborder Hexatylina Siddiqi, 1980
           Superfamily Iotonchioidea (Goodey, 1953) Siddiqi, 1986 see Superfamily Sphaerularioidea Lubbock, 1861
             1 Family Iotonchiidae Goodey, 1953
             2 Family Parasitylenchidae Siddiqi, 1986