Natura - nature
   actualia - actual entities
     Mundus Plinius - physical world
       naturalia - natural bodies
         [crown] Clade Biota Wagner 2004 [Wiemann, de Queiroz, Rowe, Planavsky, Anderson, Gogarten, Turner & Gauthier 2020]
           Domain Bacteria Woese et al. 1990 [paraphyletic?]
             Superphylum "Proteobacteria" Craig et al. 2010
               Phylum "Betaproteobacteria" Garrity et al., 2006 [monotypic]
                 Class Betaproteobacteriaᵀ Garrity et al. 2006
                   Order Hydrogenophilales Garrity et al. 2006 [monotypic]
                     Family Hydrogenophilaceaeᵀ Garrity et al. 2006
                       1 Genus Hydrogenophilusᵀ Hayashi et al. 1999
                       2 Genus Petrobacter Bonilla Salinas et al. 2004 [monotypic]
                       3 Genus Tepidiphilus Manaia et al. 2003 [monotypic]
                       4 Genus Thiobacillus Beijerinck 1904 (Approved Lists 1980)