procaryotes Domain Archaea Woese et al. 1990 Phylum Crenarchaeota Garrity and Holt 2001 Class Thermoprotei Reysenbach 2001 see Class Thermoprotei Reysenbach 2002 Order Thermoproteales Zillig and Stetter 1982 Family Thermoproteaceae Zillig and Stetter 1982 Genus Caldivirga Itoh et al. 1999