Procaryotic Genera
   Domain "Bacteria" Woese et al. 1990
     Phylum Thermotogae Reysenbach 2001 [monotypic]
       Class Thermotogae Reysenbach 2001 [monotypic] see Class Thermotogae Reysenbach 2002
         Order Thermotogalesᵀ Reysenbach 2001 [monotypic] see Order Thermotogales Reysenbach 2002
           Family Thermotogaceae Reysenbach 2001 see Family Thermotogaceae Reysenbach 2002
             1 Genus Thermotogaᵀ Stetter and Huber 1986
             2 Genus Fervidobacterium Patel et al. 1985
             3 Genus Geotoga Davey et al. 1993
             4 Genus Petrotoga Davey et al. 1993
             5 Genus Thermosipho Huber et al. 1989