procaryotes
   Domain Archaea Woese et al. 1990
     Phylum Crenarchaeota Garrity and Holt 2001
       Class Thermoprotei Reysenbach 2001 nom. inval. 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