Procaryotic Genera
   Domain "Archaea" Woese et al. 1990
     Phylum Euryarchaeota Garrity and Holt 2001
       Class Methanobacteria Boone 2001 nom. inval. [monotypic] see Class Methanobacteria Boone 2002
         Order Methanobacterialesᵀ Balch and Wolfe 1981
           Family Methanobacteriaceae Barker 1956 (Approved Lists 1980)
             1 Genus Methanobacteriumᵀ Kluyver and van Niel 1936 (Approved Lists 1980)
             2 Genus Methanobrevibacter Balch and Wolfe 1981
             3 Genus Methanosphaera Miller and Wolin 1985
             4 Genus Methanothermobacter Wasserfallen et al. 2000