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 Platyhelminthes Gegenbaur, 1859 - flatworms
           Class Trematoda Rudolphi, 1808 - flukes see Infraclass Trematoda Rudolphi, 1808
             Subclass Digenea Carus, 1863
               Order Plagiorchiida La Rue, 1957
                 Suborder Opecoelata
                   Superfamily Opecoeloidea
                     Family Opecoelidae Ozaki, 1925
                       1 Genus Cotylogonoporum Thapar & Dayal, 1934
                       2 Genus Eurycreadium Manter, 1934
                       3 Genus Helicometrina Linton, 1910
                       4 Genus Decemtestis Yamaguti, 1934
                       5 Genus Neonotoporus Srivastava, 1942
                       6 Genus Nezpercella Schell, 1974