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 Protozoa Goldfuss, 1818 see Kingdom Protozoa Goldfuss, 1818
         Phylum Sarcomastigophora Honigberg & Balamuth, 1963
           Subphylum Opalinata Wenyon, 1926 see Superclass Opalinata Wenyon, 1926
             Order Opalinida Poche, 1913
               Family Opalinidae Claus, 1874
                 1 ?Genus Bezzenbergia see Genus Bezzenbergeria Earl, 1973
                 2 ?Genus Hegneriella Earl, 1971
                 3 Genus Protoopalina Metcalf, 1918
                 4 Genus Zelleriella Metcalf, 1920, nom. nud.
                 5 Genus Cepedea Metcalf, 1920
                 6 Genus Opalina Purkinje & Valentin, 1835