[organisms] see Clade Biota Wagner 2004 [Wiemann, de Queiroz, Rowe, Planavsky, Anderson, Gogarten, Turner & Gauthier 2020]
   Domain Bacteria Woese et al. 1990
     Phylum "Proteobacteria" Garrity et al. 2005 see Superphylum Proteobacteria Craig et al. 2010
       Class Gammaproteobacteria Garrity et al. 2005
         Order Chromatiales Imhoff 2005
           Family Chromatiaceae Bavendamm 1924 (Approved Lists 1980)
             Genus Thiococcus (ex Eimhjellen et al. 1967) Imhoff et al. 1998
               Thiococcus pfennigii (Eimhjellen 1970) Imhoff et al. 1998