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 Genus Acidianus Segerer et al. 1986 Genus Metallosphaera Huber et al. 1989 Genus Stygiolobus Segerer et al. 1991 Genus Sulfurisphaera Kurosawa et al. 1998 Genus Sulfurococcus Golovacheva et al. 1995 1 Genus Sulfolobus Brock et al. 1972 (Approved Lists 1980)