procaryotes
   Domain Bacteria Woese et al. 1990 stat. inval. see Domain Bacteria Woese et al. 2024
     Phylum Proteobacteria Garrity and Holt 2001 nom. nud. see Phylum Proteobacteria Garrity et al. 2005 stat. inval.
       Class "Alphaproteobacteria" "Garrity and Holt 2001" nom. nud. see Class Alphaproteobacteria Garrity et al. 2006
         1 Order Rhodospirillales Pfennig and Trüper 1971 (Approved Lists 1980)
         2 Order Rickettsiales Gieszczykiewicz 1939 (Approved Lists 1980)
         3 Order "Rhodobacterales" "Garrity and Holt 2001" nom. nud. [monotypic] see Order Rhodobacterales Garrity et al. 2006
         4 Order "Sphingomonadales" "Garrity and Holt 2001" nom. nud. [monotypic] see Order Sphingomonadales Yabuuchi and Kosako 2006
         5 Order Caulobacterales Henrici and Johnson 1935 (Approved Lists 1980) [monotypic]
         6 Order "Rhizobiales" "Garrity and Holt 2001" nom. nud. see Order Rhizobiales Kuykendall 2006