prokaryotes - bacteria see Domain Bacteria Woese et al. 1990
   Domain "Archaea" Woese et al. 1990
     Phylum "Euryarchaeota" Garrity and Holt 2001
       Class "Methanomicrobia"
         Order Methanosarcinales Boone et al. 2002
           Family Methanosaetaceae Boone et al. 2002 nom. illeg. [monotypic]
             Genus Methanothrix Huser et al. 1983