prokaryotes - bacteria see Domain Bacteria Woese et al. 1990
   Domain "Bacteria" Woese et al. 1990
     Phylum "Aquificae" Reysenbach 2001 [monotypic]
       Class Aquificae Reysenbach 2002 [monotypic]
         Order Aquificales Reysenbach 2002
           1 Family Aquificaceae Reysenbach 2002
           2 Family Desulfurobacteriaceae L'Haridon et al. 2006
           3 Family Hydrogenothermaceae Eder and Huber 2003
           4 Genus Thermosulfidibacter Nunoura et al. 2008, incertae sedis