procaryotes
   Domain Archaea Woese et al. 1990
     Phylum Euryarchaeota Garrity and Holt 2001
       Class Thermococci Zillig and Reysenbach 2001 see Class Thermococci Zillig and Reysenbach 2002
         Order Thermococcales Zillig 1988
           1 Family Thermococcaceae Zillig 1988