Natura - nature
   actualia - actual entities
     Mundus Plinius - physical world
       naturalia - natural bodies
         [crown] Clade Biota Wagner 2004 [Wiemann, de Queiroz, Rowe, Planavsky, Anderson, Gogarten, Turner & Gauthier 2020]
           Clade neomura Cavalier-Smith, 1987
             Domain Archaea Woese et al. 1990 [paraphyletic]
               Phylum Euryarchaeota Garrity and Holt 2001
                 Class "Methanomicrobia"
                   Order Methanomicrobialesᵀ Balch and Wolfe 1981
                     Family Methanocalculaceae Zhilina et al. 2014 [monotypic]
                       Genus Methanocalculusᵀ Ollivier et al. 1998
                         1 Methanocalculus chunghsingensis Lai et al. 2004
                         2 Methanocalculus halotolerans Ollivier et al. 1998
                         3 Methanocalculus natronophilus Zhilina et al. 2014
                         4 Methanocalculus pumilus Mori et al. 2000
                         5 Methanocalculus taiwanensis Lai et al. 2002