Procaryotic Genera Domain "Archaea" Woese et al. 1990 Phylum Crenarchaeota Garrity and Holt 2001 [monotypic] Class Thermoprotei Reysenbach 2001 see Class Thermoprotei Reysenbach 2002 Order Sulfolobales Stetter 1989 [monotypic] Family Sulfolobaceae Stetter 1989 Genus Metallosphaera Huber et al. 1989