Natura - nature
   actualia - actual entities
     Mundus Plinius - physical world
       naturalia - natural bodies
         Clade Biota Wagner 2004 [Wiemann, de Queiroz, Rowe, Planavsky, Anderson, Gogarten, Turner & Gauthier 2020]
           Domain Bacteria Woese et al. 2024
             Kingdom Pseudomonadati (Gibbons and Murray 1978) Oren and Göker 2024
               Phylum Pseudomonadotaᵀ Garrity et al. 2021
                 Class Alphaproteobacteria Garrity et al. 2006
                   Order Rhodospirillales Pfennig and Trüper 1971 (Approved Lists 1980)
                     01 Genus "Candidatus Riegeria" Gruber-Vodicka et al. 2020, incertae sedis
                     02 Family Acetobacteraceae (ex Henrici 1939) Gillis and De Ley 1980
                     03 Family Aestuariispiraceae Hu et al. 2025
                     04 Family Allostellaceae Deshmukh and Oren 2025
                     05 Family Azospirillaceae Hördt et al. 2020
                     06 Family Geminicoccaceae Proença et al. 2018
                     07 Family Kiloniellaceae Wiese et al. 2009
                     08 Family Oleispirillaceae Peng et al. 2024 [monotypic]
                     09 Family Reyranellaceae Hördt et al. 2020 [monotypic]
                     10 Family Rhodospirillaceae Pfennig and Trüper 1971 (Approved Lists 1980)
                     11 Family Rhodovibrionaceae Hördt et al. 2020
                     12 Family Roseiterribacteraceae Nakai et al. 2024 [monotypic]
                     13 Family Shumkoniaceae Yang et al. 2025 [monotypic]
                     14 Family Terasakiellaceae Hördt et al. 2020 [monotypic]
                     15 Family Thalassobaculaceae Hördt et al. 2020
                     16 Family Thalassospiraceae Hördt et al. 2020
                     17 Family Zavarziniaceae Hördt et al. 2020 [monotypic]