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 Gammaproteobacteriaᵀ Garrity et al. 2005
                   Order Beggiatoales Buchanan 1957 (Approved Lists 1980)
                     1 Family Achromatiaceae Massart 1901 (Approved Lists 1980) [monotypic]
                     2 Family Beggiatoaceaeᵀ Migula 1894 (Approved Lists 1980)
                     3 Family Fastidiosibacteraceae Xiao et al. 2018
                     4 Family Francisellaceae Sjöstedt 2005
                     5 Family Leucotrichaceae Buchanan 1957 (Approved Lists 1980)
                     6 Family Piscirickettsiaceae Fryer and Lannan 2005