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
                       1 Genus Methylocystisᵀ (ex Whittenbury et al. 1970) Bowman et al. 1993
                       2 Genus Albibacter Doronina et al. 2001 [monotypic]
                       3 Genus Hansschlegelia Ivanova et al. 2010
                       4 Genus Methylopila Doronina et al. 1998
                       5 Genus Methylosinus (ex Whittenbury et al. 1970) Bowman et al. 1993
                       6 Genus Pleomorphomonas Xie and Yokota 2005
                       7 Genus Terasakiella Satomi et al. 2002 [monotypic]