living organisms see Clade Biota Wagner 2004 [Wiemann, de Queiroz, Rowe, Planavsky, Anderson, Gogarten, Turner & Gauthier 2020]
   Superkingdom Eukaryotae see Domain Eukaryota Chatton, 1925
     Kingdom Animalia Linnaeus, 1758 - animals
       Subkingdom Eumetazoa Butschli, 1910 see [unranked] Eumetazoa Bütschli, 1910
         Phylum Nemata Cobb, 1919 see Phylum Nematoda Gegenbaur, 1859
           Class Adenophorea
             Subclass Enoplia Pearse, 1942
               Order Mermithida Hyman, 1951
                 Suborder Mermithina Andrassy, 1971
                   Superfamily Tetradonematoidea see Superfamily Mermithoidea Braun, 1883
                     Family Tetradonematidae Cobb, 1919
                       1 Genus Tetradonema Cobb, 1919
                       2 Genus Heterogonema Van Waerebeke & Remillet, 1971
                       3 Genus Aproctonema Keilin, 1917
                       4 Genus Corethrellonema
                       5 Genus Mermithonema Goodey, 1941