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 Secernentea Von Linstow, 1905
             Subclass Spiruria see Subclass Plectia Hodda, 2007
               Order Spirurida Railliet, 1914
                 Suborder Spirurina Railliet & Henry, 1915
                   Superfamily Physalopteroidea Railliet, 1893 see Superfamily Camallanoidea Railliet & Henry, 1915
                     Family Gnathostomatidae Railliet, 1895
                       1 Genus Gnathostoma Owen, 1837
                       2 Genus Spiroxys Schneider, 1866
                       3 Genus Echinocephalus Molin, 1858
                       4 Genus Tanqua Blanchard, 1904