[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 Methanococci Boone 2002
         Order Methanococcales Balch and Wolfe 1981
           Family Methanococcaceae Balch and Wolfe 1981
             1 Genus Methanococcus Kluyver and van Niel 1936 (Approved Lists 1980)
             2 Genus Methanothermococcus Whitman 2002