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 Rhigonematina Inglis, 1983
               Superfamily Rhigonematoidea Artigas, 1930
                 1 Family Ichthyocephalidae Travassos & Kloss, 1958
                 2 Family Rhigonematidae Artigas, 1930
                 3 Family Xustromatidae Hodda, 2011, nom. null. see Family Xustrostomatidae Hunt, 2002