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 Bacteroidota Krieg et al. 2021
                 Class Cytophagia Nakagawa 2012 [monotypic]
                   Order Cytophagalesᵀ Leadbetter 1974 (Approved Lists 1980)
                     Family Flexibacteraceae García-López et al. 2020 [monotypic]
                       Genus Flexibacterᵀ Soriano 1945 (Approved Lists 1980)
                         1 Flexibacter aggregans (Lewin 1969) Leadbetter 1974 (Approved Lists 1980)
                         2 Flexibacter aurantiacus Lewin 1969 (Approved Lists 1980)
                         3 Flexibacter canadensis Christensen 1980
                         4 Flexibacter elegans (ex Lewin 1969) Reichenbach 1989
                         5 Flexibacter flexilis Soriano 1945 (Approved Lists 1980)
                         6 Flexibacter litoralis Lewin 1969 (Approved Lists 1980)
                         7 Flexibacter polymorphus Lewin 1974 (Approved Lists 1980)
                         8 Flexibacter roseolus Lewin 1969 (Approved Lists 1980)
                         9 Flexibacter ruber Lewin 1969 (Approved Lists 1980)