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 "Proteobacteria" Craig et al. 2010
               Phylum "Betaproteobacteria" Garrity et al., 2006 [monotypic]
                 Class Betaproteobacteriaᵀ Garrity et al. 2006
                   Order Rhodocyclales Garrity et al. 2006 [monotypic]
                     Family Rhodocyclaceaeᵀ Garrity et al. 2006
                       Genus Rhodocyclusᵀ Pfennig 1978 (Approved Lists 1980)
                         1 Rhodocyclus purpureusᵀ Pfennig 1978 (Approved Lists 1980)
                         2 Rhodocyclus tenuis (Pfennig 1969) Imhoff et al. 1984