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 "Gammaproteobacteria" Garrity et al., 2005 [monotypic]
                 Class Gammaproteobacteriaᵀ Garrity et al. 2005
                   Order "Enterobacteriales" Garrity and Holt 2001 nom. nud. [monotypic]
                     Family Enterobacteriaceaeᵀ Rahn 1937 (Approved Lists 1980)
                       Genus Providencia Ewing 1962 (Approved Lists 1980)
                         1 Providencia alcalifaciens (de Salles Gomes 1944) Ewing 1962 (Approved Lists 1980)
                         2 Providencia burhodogranariea Juneja and Lazzaro 2009
                         3 Providencia heimbachae Müller et al. 1986
                         4 Providencia rustigianii Hickman-Brenner et al. 1983
                         5 Providencia sneebia Juneja and Lazzaro 2009
                         6 Providencia stuartii (Buttiaux et al. 1954) Ewing 1962 (Approved Lists 1980)
                         7 Providencia vermicola Somvanshi et al. 2006