prokaryotes - bacteria see Domain Bacteria Woese et al. 1990 Domain "Archaea" Woese et al. 1990 Phylum "Euryarchaeota" Garrity and Holt 2001 Class Methanopyri Garrity and Holt 2002 [monotypic] Order Methanopyrales Huber and Stetter 2002 [monotypic] Family Methanopyraceae Huber and Stetter 2002 [monotypic] Genus Methanopyrus Kurr et al. 1992