prokaryotes - bacteria see Domain Bacteria Woese et al. 1990 Domain "Archaea" Woese et al. 1990 Phylum "Euryarchaeota" Garrity and Holt 2001 Class Thermoplasmata Reysenbach 2002 [monotypic] Order Thermoplasmatales Reysenbach 2002 Family Picrophilaceae Schleper et al. 1996 [monotypic] 1 Genus Picrophilus Schleper et al. 1996