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
           1 Family Methanosaetaceae Boone et al. 2002 nom. illeg. [monotypic]
           2 Family Methanosarcinaceae Balch and Wolfe 1981
           3 Family Methermicoccaceae Cheng et al. 2007 [monotypic]