Concise hierarchy

(Kingdom) Pseudomonadati - (Phylum) Pseudomonadota - (Class) Alphaproteobacteria

Current position

Alphaproteobacteria (Class) Garrity et al. 2006

Ref: LPSN, 2020-present: [24 Apr 2026]; LPSN[24 Apr 2026].

Alternative positions

Alphabacteria (Class) Cavalier-Smith 2002 nom. rej.	Ref: T. Cavalier-Smith, 2002a: tbl. 1 (p. 12). [new position]
Alphaproteobacteria (Class) "Garrity and Holt 2001" nom. nud.	Ref: G.M. Garrity et al., 2001b: 6.
Rickettsias ([unranked])	Ref: E. Weiss, 1982: 40.
Scotobacteria (Class) Gibbons and Murray 1978 (Approved Lists 1980)	Ref: N.R. Krieg & J.G. Holt, 1984-1989

Historical positions

Alphaproteobacteria (Class) Garrity et al. 2006	Ref: J.P. Euzéby, 2016: [1 Sep 2017].
Alphaproteobacteria (Class) Garrity et al. 2006	Ref: M.A. Ruggiero et al., 2015b: table 2 (p. 5).
Alphaproteobacteria (Class) Garrity et al. 2006	Ref: G.M. Garrity et al., 2007: 62.
Alphabacteria (Class) Cavalier-Smith 2002 nom. rej.	Ref: T. Cavalier-Smith, 2002a: tbl. 1 (p. 12). [new position]
Alphaproteobacteria (Class) "Garrity and Holt 2001" nom. nud.	Ref: G.M. Garrity et al., 2001b: 6.
Alphaproteobacteria (Class) "Garrity and Holt 2001" nom. nud.	Ref: G.M. Garrity & J.G. Holt, 2001a: 157.
Scotobacteria (Class) Gibbons and Murray 1978 (Approved Lists 1980)	Ref: N.R. Krieg & J.G. Holt, 1984-1989
Rickettsias ([unranked])	Ref: E. Weiss, 1982: 40.

Number of Subtaxa

2026	Available in Systema Naturae 2000	6f;41g;51s
1989-present	Systema Naturae 2000: 24 Apr 2026	[6f;41g]
2016	J.P. Euzéby: [11 Sep 2017]	[3f;13g]
2007	G.M. Garrity et al.	[3f;16g;62s]
2001b	G.M. Garrity et al.: 6	[3f;17g]
2001a	G.M. Garrity & J.G. Holt: 158	[3f;15g]
2000		3f15g
1982	E. Weiss	3f