Procaryotic Genera
   Domain "Bacteria" Woese et al. 1990
     Phylum Proteobacteria Garrity and Holt 2001 see Phylum Proteobacteria Garrity et al. 2005
       Class "Alphaproteobacteria" Garrity and Holt 2001 nom. nud. see Class Alphaproteobacteria Garrity et al. 2006
         Order "Rhizobiales" see Order Rhizobiales Kuykendall 2006
           Family Rhizobiaceae Conn 1938 (Approved Lists 1980)
             Genus Rhizobium Frank 1889 (Approved Lists 1980)