Procaryotic Genera Domain "Archaea" Woese et al. 1990 Phylum Euryarchaeota Garrity and Holt 2001 1 Class Methanobacteria Boone 2001 nom. inval. [monotypic] see Class Methanobacteria Boone 2002 2 Class Methanococci Boone 2001 nom. inval. see Class Methanococci Boone 2002 3 Class Halobacteria Grant et al. 2001 [monotypic] see Class Halobacteria Grant et al. 2002 4 Class Thermoplasmata Reysenbach 2001 [monotypic] see Class Thermoplasmata Reysenbach 2002 5 Class Thermococci Zillig and Reysenbach 2001 [monotypic] see Class Thermococci Zillig and Reysenbach 2002 6 Class Archaeoglobi Garrity and Holt 2001 nom. inval. [monotypic] see Class Archaeoglobi Garrity and Holt 2002 7 Class Methanopyri Garrity and Holt 2001 nom. inval. [monotypic] see Class Methanopyri Garrity and Holt 2002