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 Methanomicrobiaceaeᵀ Balch and Wolfe 1981
                       Genus Methanogenium Romesser et al. 1981
                         1 Methanogenium cariaci Romesser et al. 1981
                         2 Methanogenium frigidum Franzmann et al. 1997
                         3 Methanogenium marinum Chong et al. 2003
                         4 Methanogenium organophilum Widdel et al. 1989