Natura - nature
   actualia - actual entities
     Mundus Plinius - physical world
       naturalia - natural bodies
         [crown] Clade Biota Wagner 2004 [Wiemann, de Queiroz, Rowe, Planavsky, Anderson, Gogarten, Turner & Gauthier 2020]
           Domain Bacteria Woese et al. 1990 [paraphyletic?]
             Superphylum Terrabacteria Battistuzzi et al. 2004
               Phylum Firmicutes corrig. Gibbons and Murray 1978 (Approved Lists 1980)
                 Class Negativicutes Marchandin et al. 2010 [monotypic]
                   Order Selenomonadales Marchandin et al. 2010
                     Family Selenomonadaceaeᵀ Campbell et al. 2015
                       Genus Selenomonasᵀ von Prowazek 1913 (Approved Lists 1980)
                         Selenomonas ruminantium (Certes 1889) Wenyon 1926 (Approved Lists 1980)
                           Selenomonas ruminantium subsp. ruminantiumᵀ (Certes 1889) Bryant 1956 (Approved Lists 1980)