[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
           1 Family Methanobacteriaceae Barker 1956 (Approved Lists 1980)
           2 Family Methanothermaceae Stetter 1982