prokaryotes - bacteria see Domain Bacteria Woese et al. 1990
   Domain "Archaea" Woese et al. 1990
     Phylum "Crenarchaeota" Garrity and Holt 2001 [monotypic]
       Class Thermoprotei Reysenbach 2002
         Order Cenarchaeales Cavalier-Smith 2002 [monotypic]
           Family "Cenarchaeaceae" DeLong and Preston 1996 [monotypic]
             Genus "Cenarchaeum" DeLong and Preston 1996