[organisms] see Clade Biota Wagner 2004 [Wiemann, de Queiroz, Rowe, Planavsky, Anderson, Gogarten, Turner & Gauthier 2020]
   Domain "Archaea" Woese et al. 1990
     Phylum "Euryarchaeota" Garrity and Holt 2001
       Class Methanobacteria Boone 2002
         Order Methanobacteriales Balch and Wolfe 1981
           Family Methanobacteriaceae Barker 1956 (Approved Lists 1980)
             Genus Methanobacterium Kluyver and van Niel 1936 (Approved Lists 1980)
               Methanobacterium thermaggregans corrig. Blotevogel and Fischer 1988