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 Terrabacteria Battistuzzi et al. 2004
               Phylum Firmicutes corrig. Gibbons and Murray 1978 (Approved Lists 1980)
                 Class Clostridia Rainey 2010
                   Order Clostridialesᵀ Prévot 1953 (Approved Lists 1980)
                     Family Heliobacteriaceae Madigan and Asao 2010
                       Genus Heliobacteriumᵀ Gest and Favinger 1985
                         1 Heliobacterium chlorumᵀ Gest and Favinger 1985
                         2 Heliobacterium gestii Ormerod et al. 1996
                         3 Heliobacterium modesticaldum Kimble et al. 1996
                         4 Heliobacterium sulfidophilum Bryantseva et al. 2001
                         5 Heliobacterium undosum Bryantseva et al. 2001