procaryotes Domain Archaea Woese et al. 1990 stat. inval. see Domain Archaea Woese et al. 2024 Phylum Crenarchaeota Garrity and Holt 2001 [monotypic] Class Thermoprotei Reysenbach 2001 nom. inval. see Class Thermoprotei Reysenbach 2002 Order Sulfolobales Stetter 1989 [monotypic] Family Sulfolobaceae Stetter 1989 Genus Stygiolobus Segerer et al. 1991