organisms see Clade Biota Wagner 2004 [Wiemann, de Queiroz, Rowe, Planavsky, Anderson, Gogarten, Turner & Gauthier 2020]
   Domain eukaryotes see Domain Eukaryota Chatton, 1925
     stramenopiles Patterson, 1990, nom. vernac. see [unranked] Stramenopiles Patterson, 1990
       Order Slopalinida Patterson, 1989 see Phylum Opalinata Wenyon, 1926
         Family Opalinidae Claus, 1874
           1 Genus Protozelleriella Delvinquier, Markus & Passmore, 1991
           2 Genus Zelleriella Metcalf, 1920, nom. nud.
           3 Genus Protoopalina Metcalf, 1918
           4 Genus Cepedea Metcalf, 1920
           5 Genus Opalina Purkinje & Valentin, 1835
           6 Genus Bezzenbergeria Earl, 1973
           7 Genus Hegneriella Earl, 1971