prokaryotes - bacteria see Domain Bacteria Woese et al. 1990
   Domain "Archaea" Woese et al. 1990
     Phylum "Crenarchaeota" Garrity and Holt 2001 [monotypic]
       Class Thermoprotei Reysenbach 2002
         Order Sulfolobales Stetter 1989 [monotypic]
           Family Sulfolobaceae Stetter 1989
             1 Genus Acidianus Segerer et al. 1986
             2 Genus Desulfurolobus Zillig and Böck 1987 see Genus Acidianus Segerer et al. 1986
             3 Genus Metallosphaera Huber et al. 1989
             4 Genus Stygiolobus Segerer et al. 1991
             5 Genus Sulfolobus Brock et al. 1972 (Approved Lists 1980)
             6 Genus Sulfurisphaera Kurosawa et al. 1998
             7 Genus Sulfurococcus Golovacheva et al. 1995