prokaryotes - bacteria see Domain Bacteria Woese et al. 1990
   Domain "Bacteria" Woese et al. 1990
     Phylum "Bacteroidetes" Krieg et al. 2012
       Class Bacteroidia Krieg 2012 [monotypic]
         Order Bacteroidales Krieg 2012
           Family Rikenellaceae Krieg et al. 2012
             Genus Rikenella Collins et al. 1985