[organisms] see Clade Biota Wagner 2004 [Wiemann, de Queiroz, Rowe, Planavsky, Anderson, Gogarten, Turner & Gauthier 2020]
   Domain Bacteria Woese et al. 1990
     Phylum "Proteobacteria" Garrity et al. 2005 see Superphylum Proteobacteria Craig et al. 2010
       Class Betaproteobacteria Garrity et al. 2006
         Order Rhodocyclales Garrity et al. 2006
           Family Rhodocyclaceae Garrity et al. 2006
             Genus Rhodocyclus Pfennig 1978 (Approved Lists 1980)
               1 Rhodocyclus purpureus Pfennig 1978 (Approved Lists 1980)
               2 Rhodocyclus tenuis (Pfennig 1969) Imhoff et al. 1984