[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 Methanothermaceae Stetter 1982
             Genus Methanothermus Stetter 1982
               1 Methanothermus fervidus Stetter 1982
               2 Methanothermus sociabilis Stetter 1986