organisms see Clade Biota Wagner 2004 [Wiemann, de Queiroz, Rowe, Planavsky, Anderson, Gogarten, Turner & Gauthier 2020]
   Domain eukaryotes see Domain Eukaryota Chatton, 1925
     alveolates Cavalier-Smith see [unranked] Alveolata Cavalier-Smith, 1991
       Phylum Ciliophora Doflein, 1901 - ciliates
         Subphylum Intramacronucleata Lynn, 1996 - amphiesmates
           Class Oligohymenophorea de Puytorac et al., 1974 - oligohymenophoreans
             Subclass Peritrichia Stein, 1859
               Order Sessilida Kahl, 1933
                 Family Operculariidae Fauré-Fremiet, in Corliss, 1979
                   1 Genus Bezedniella Stloukal & Matis, 1994
                   2 Genus Opercularia Goldfuss, 1820
                   3 Genus Orbopercularia Lust, 1950
                   4 Genus Propyxidium Corliss, 1979
                   5 Genus Ampullaster Jankowski, 1976, nom. inval.