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 Ciliophora Doflein, 1901 - ciliates
           Class Polyhymenophora Jankowski, 1967 see Class Spirotrichea Bütschli, 1889
             Subclass Spirotricha see Class Spirotrichea Bütschli, 1889
               Order Heterotrichida Stein, 1859 - heterotrichs
                 Suborder Heterotrichina see Order Heterotrichida Stein, 1859
                   Family Metopidae Kahl, 1927
                     1 Genus Metopusᵀ Claparède & Lachmann, 1858
                     3 Genus Bothrostoma Stokes, 1888
                     4 Genus Brachonella Jankowski, 1964
                     5 Genus Palmarella Jankowski, 1975
                     6 Genus Spirorhynchus da Cunha, 1915
                     7 Genus Tesnospira Jankowski, 1964
                     8 Genus Tropidoatractus Levander, 1894