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 Hyphomicrobiales Douglas 1957 (Approved Lists 1980)
                     Family Xanthobacteraceae Lee et al. 2005
                       1 Genus Ancylobacter Raj 1983
                       2 Genus Aquabacter Irgens et al. 1993 [monotypic]
                       3 Genus Azorhizobium Dreyfus et al. 1988
                       4 Genus Labrys Vasilyeva and Semenov 1985
                       5 Genus Roseixanthobacter Soltysiak et al. 2025
                       6 Genus Xanthobacterᵀ Wiegel et al. 1978 (Approved Lists 1980)