prokaryotes - bacteria see Domain Bacteria Woese et al. 1990
   Domain "Bacteria" Woese et al. 1990
     Phylum "Thermotogae" Reysenbach 2001 [monotypic]
       Class Thermotogae Reysenbach 2002
         Order Kosmotogales Bhandari and Gupta 2014 [monotypic]
           Family Kosmotogaceae Bhandari and Gupta 2014
             1 Genus Kosmotoga DiPippo et al. 2009
             2 Genus Mesotoga Nesbø et al. 2013