[organisms] see Clade Biota Wagner 2004 [Wiemann, de Queiroz, Rowe, Planavsky, Anderson, Gogarten, Turner & Gauthier 2020]
   Domain Bacteria Woese et al. 1990 stat. inval. see Domain Bacteria Woese et al. 2024
     Phylum "Proteobacteria" Garrity et al. 2005 stat. inval. see Phylum Pseudomonadota Garrity et al. 2021
       Class Alphaproteobacteria Garrity et al. 2006
         1 Order Rhodospirillales Pfennig and Trüper 1971 (Approved Lists 1980)
         2 Order Kordiimonadales Kwon et al. 2005
         3 Order Rickettsiales Gieszczykiewicz 1939 (Approved Lists 1980)
         4 Order Rhodobacterales Garrity et al. 2006
         5 Order Sphingomonadales Yabuuchi and Kosako 2006
         6 Order Caulobacterales Henrici and Johnson 1935 (Approved Lists 1980)
         7 Order Rhizobiales Kuykendall 2006 see Order Hyphomicrobiales Douglas 1957 (Approved Lists 1980)
         8 Order "Parvularculales" Garrity et al. 2003 nom. nud.