Rhodospirillales Pfennig and Trüper 1971 (Approved Lists 1980) emend. Hördt et al. 2020 Rhodospirillum Molisch 1907 (Approved Lists 1980) emend. Lakshmi et al. 2014 Universal Root Woese et al. 1990 Bacteria (None 2015) Woese et al. 1990 Proteobacteria (sic) Garrity et al. 2021 Pseudomonadota corrig. Garrity et al. 2021 Alphaproteobacteriota (sic) Garrity et al. 2021 Alphaproteobacteria Garrity et al. 2006 Rhodospirillales Pfennig and Trüper 1971 (Approved Lists 1980) emend. Hördt et al. 2020 Alphaproteobacteria Garrity et al. 2006 Parvularculales Garrity et al. 2003 Rhizobiales Kuykendall 2006 Kordiimonadales Kwon et al. 2005 emend. Hördt et al. 2020 Rickettsiales Gieszczykiewicz 1939 (Approved Lists 1980) emend. Dumler et al. 2001 Rhodobacterales Garrity et al. 2006 emend. Hördt et al. 2020 Sphingomonadales Yabuuchi and Kosako 2006 emend. Hördt et al. 2020 Caulobacterales Henrici and Johnson 1935 (Approved Lists 1980) Sneathiellales Kurahashi et al. 2008 Kiloniellales Wiese et al. 2009 Hyphomicrobiales Douglas 1957 (Approved Lists 1980) emend. Hördt et al. 2020 Incertae sedis 23 None 2015 Magnetococcales Bazylinski et al. 2013 Incertae sedis 91 None 2015 Incertae sedis 136 None 2015 Incertae sedis 154 None 2015 Incertae sedis 120 Tirandaz et al. 2015 Iodidimonadales Iino et al. 2016 Emcibacterales Iino et al. 2016 Micropepsales Harbison et al. 2017 Rhodothalassiales Venkata Ramana et al. 2014 Incertae sedis 70 None 2015 Incertae sedis 224 Kragelund et al. 2006 Incertae sedis 221 Kragelund et al. 2006 Incertae sedis 263 Kwan et al. 2012 Incertae sedis 265 Anderson and Haygood 2007 Incertae sedis 275 Bing et al. 2013 Incertae sedis 326 Horn et al. 1999 Pelagibacterales Grote et al. 2012 Minwuiales Sun et al. 2018 Holosporales Szokoli et al. 2020 Hyphomonadales Kevbrin et al. 2021 Maricaulales Kevbrin et al. 2021 Methylospongiales Podell et al. 2020 Incertae sedis 667 Kanamori et al. 2002 Rhodospirillaceae Pfennig and Trüper 1971 (Approved Lists 1980) emend. Hördt et al. 2020 Acetobacteraceae (ex Henrici 1939) Gillis and De Ley 1980 emend. Hördt et al. 2020 Geminicoccaceae Proença et al. 2018 emend. Hördt et al. 2020 Incertae sedis 288 Gruber-Vodicka et al. 2011 Incertae sedis 544 Thiel et al. 2016 Elioraeaceae Habib et al. 2020 Azospirillaceae Hördt et al. 2020 Kiloniellaceae Wiese et al. 2009 emend. Hördt et al. 2020 Proença D.N. Whitman W.B. Varghese N. Shapiro N. Woyke T. Kyrpides N.C. Morais P.V. Arboriscoccus pini gen. nov., sp. nov., an endophyte from a pine tree of the class Alphaproteobacteria, emended description of Geminicoccus roseus, and proposal of Geminicoccaceae fam. nov. 2018 41 2 94 100 Systematic and Applied Microbiology Syst Appl Microbiol 0723-2020 10.1016/j.syapm.2017.11.006 29325988 Gruber-Vodicka H.R. Dirks U. Leisch N. Baranyi C. Stoecker K. Bulgheresi S. Heindl N.R. Horn M. Lott C. Loy A. Wagner M. Ott J. Paracatenula, an ancient symbiosis between thiotrophic Alphaproteobacteria and catenulid flatworms. 2011 108 29 12078 12083 Proceedings of the National Academy of Sciences of the United States of America Proc Natl Acad Sci U S A 0027-8424 1091-6490 10.1073/pnas.1105347108 21709249 Gibbons N.E. Murray R.G.E. Proposals concerning the higher taxa of Bacteria 1978 28 1 1 6 International Journal of Systematic Bacteriology Int J Syst Bacteriol 0020-7713 10.1099/00207713-28-1-1 Thiel V. Wood J.M. Olsen M.T. Tank M. Klatt C.G. Ward D.M. Bryant D.A. The Dark Side of the Mushroom Spring Microbial Mat: Life in the Shadow of Chlorophototrophs. I. Microbial Diversity Based on 16S rRNA Gene Amplicons and Metagenomic Sequencing. 2016 7 919 919 Frontiers in Microbiology Front. Microbio. 1664-302X 10.3389/fmicb.2016.00919 27379049 Garrity G.M. Bell J.A. Lilburn T. Garrity G.M. Brenner D.J. Krieg N.R. Staley J.T. Class I. Alphaproteobacteria class. nov. 2005 2, Part C 2 1 Bergey's Manual of Systematic Bacteriology Springer New York 0387241450 Habib N. Khan I.U. Xiao M. Hejazi M.S. Tarhriz V. Zhi X.-Y. Li W.-J. Elioraea thermophila sp. nov., a thermophilic bacterium from hot spring of the class Alphaproteobacteria, emended description of the genus Elioraea and proposal of Elioraeaceae fam. nov. 2020 70 2 1300 1306 International Journal of Systematic and Evolutionary Microbiology Int J Syst Evol Microbiol 1466-5026 1466-5034 10.1099/ijsem.0.003915 31804917 Pfennig N. Trüper H.G. Higher taxa of the phototrophic bacteria. 1971 21 1 17 18 International Journal of Systematic Bacteriology Int J Syst Bacteriol 0020-7713 10.1099/00207713-21-1-17 Gillis M. De Ley J. Intra- and intergeneric similarities of the ribosomal ribonucleic acid cistrons of Acetobacter and Gluconobacter 1980 30 1 7 27 International Journal of Systematic Bacteriology Int J Syst Bacteriol 0020-7713 10.1099/00207713-30-1-7 Hördt A. García-López M. Meier-Kolthoff J.P. Tindall B.J. Weinhold L.-M. Gronow S. Kyrpides N. Woyke T. Schleuning M. Göker M. Analysis of 1,000+ Type-Strain Genomes Substantially Improves Taxonomic Classification of Alphaproteobacteria 2020 11 468 Frontiers in Microbiology Front. Microbio. 1664-302X 10.3389/fmicb.2020.00468 32373076 TODO (garrity) RFO: The placement of Rhodospirillales into Alphaproteobacteria was essentially a unification, but Anoxyphotobacteriae has priority.