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 Methanosarcinaceae Balch and Wolfe 1981
             Genus Methanimicrococcus corrig. Sprenger et al. 2000