Domain Bacteria Woese et al. 1990 stat. inval. see Domain Bacteria Woese et al. 2024
   Phylum Thermotogae Margulis and Schwartz 1998 nom. ined. - thermophilic fermenters see Phylum Thermotogae Reysenbach 2002 stat. inval.
     1 Class Thermotogae Reysenbach 2001 nom. inval. see Class Thermotogae Reysenbach 2002