Kingdom Bacteria Cavalier-Smith 2002 - bacteria see Domain Bacteria Woese et al. 1990
   Subkingdom Unibacteria Cavalier-Smith 2002 see Domain Bacteria Woese et al. 1990
     Division Archaebacteria Cavalier-Smith 2002 see Domain Archaea Woese et al. 1990
       Subdivision Crenarchaeota Cavalier-Smith 2002 see Phylum Crenarchaeota Garrity and Holt 2001
         1 Class Crenarchaeota Cavalier-Smith 2002 see Class Thermoprotei Reysenbach 2002