Kingdom Animalia Linnaeus, 1758 - animals
   Phylum Nematoda Gegenbaur, 1859 - round worms
     Class Chromadorea Inglis, 1983
       Subclass Plectia Hodda, 2007
         Superorder Rhabditica Hodda, 2007
           Order Spirurida Railliet, 1914
             Suborder Ascaridina Inglis, 1983
               Superfamily Cosmocercoidea Railliet, 1916
                 1 Family Atractidae Railliet, 1917
                 2 Family Cosmocercidae Railliet, 1916
                 3 Family Kathlaniidae Lane, 1914