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 Euryarchaeota Cavalier-Smith 2002 see Phylum Euryarchaeota Garrity and Holt 2001
         Superclass Eurythermea Cavalier-Smith 2002
           1 Class Protoarchaea Cavalier-Smith 2002 see Class Thermococci Zillig and Reysenbach 2002
           2 Class Picrophilea Cavalier-Smith 2002