Kingdom Bacteria Cavalier-Smith 2002 stat. inval. [paraphyletic?] - bacteria see Domain Bacteria Woese et al. 1990 stat. inval.
   Subkingdom Unibacteria Cavalier-Smith 2002 [paraphyletic?] see Domain Bacteria Woese et al. 1990 stat. inval.
     Division Archaebacteria Cavalier-Smith 2002 see Domain Archaea Woese et al. 1990 stat. inval.
       Subdivision Euryarchaeota Cavalier-Smith 2002 see Phylum Euryarchaeota Garrity and Holt 2002 stat. inval.
         Superclass Eurythermea Cavalier-Smith 2002 [paraphyletic?]
           Class Picrophilea Cavalier-Smith 2002 nom. rej. [monotypic] see Class Thermoplasmata Reysenbach 2002
             Order Picrophilalesᵀ Cavalier-Smith 2002 nom. rej. see Order Thermoplasmatales Reysenbach 2002
               1 Genus Picrophilusᵀ Schleper et al. 1996