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
                 Candidate order Altiarchaeales Probst et al. 2014
                 Class "Hadesarchaea (SAGMEG)" Baker et al. 2016
                 Candidate class Methanofastidiosa (WSA2 / Arc I) Nobu et al. 2016
                 1 Candidatus Aciduliprofundum boonei Schouten et al. 2008, incertae sedis
                 2 Class Methanobacteria Boone 2002 [monotypic]
                 3.1.1 Class Methanococci Boone 2002 [monotypic]
                 3.1.2 Class "Methanomicrobia"
                 3.2 Class Halobacteria Grant et al. 2002 [monotypic]
                 4.1 Class Thermoplasmata Reysenbach 2002 [monotypic]
                 4.2 Class Thermococci Zillig and Reysenbach 2002 [monotypic]
                 4.3 Class Archaeoglobi Garrity and Holt 2002 [monotypic]
                 5 Class Methanopyri Garrity and Holt 2002 [monotypic]