procaryotes
   Domain Archaea Woese et al. 1990
     Phylum Crenarchaeota Garrity and Holt 2001
       Class Thermoprotei Reysenbach 2001 see Class Thermoprotei Reysenbach 2002
         Order Sulfolobales Stetter 1989
           Family Sulfolobaceae Stetter 1989
             1 Genus Sulfolobus Brock et al. 1972 (Approved Lists 1980)
             2 Genus Acidianus Segerer et al. 1986
             3 Genus Metallosphaera Huber et al. 1989
             4 Genus Stygiolobus Segerer et al. 1991
             5 Genus Sulfurisphaera Kurosawa et al. 1998
             6 Genus Sulfurococcus Golovacheva et al. 1995