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 "Alphaproteobacteria" Garrity et al., 2006 [monotypic]
                 Class Alphaproteobacteriaᵀ Garrity et al. 2006
                   Order Rhizobiales Kuykendall 2006
                     Family Methylocystaceae Bowman 2006
                       Genus Methylocystisᵀ (ex Whittenbury et al. 1970) Bowman et al. 1993
                         1 Methylocystis bryophila Belova et al. 2013
                         2 Methylocystis echinoides (ex Gal'chenko et al. 1977) Bowman et al. 1993
                         3 Methylocystis heyeri Dedysh et al. 2007
                         4 Methylocystis hirsuta Lindner et al. 2007
                         5 Methylocystis parvus (ex Whittenbury et al. 1970) Bowman et al. 1993
                         6 Methylocystis rosea Wartiainen et al. 2006