Domain Bacteria Woese et al. 1990
   Phylum Bacteroidetes Garrity and Holt 2001 see Phylum Bacteroidetes Krieg et al. 2012
     Class "Bacteroides" Castellani & Chalmers, 1919 emend. Shah & Collins, 1989 emend. Shah & Collins, 1989 see Class Bacteroidia Krieg et al., 2012
       Order "Bacteroidales" Krieg 2012 see Order Bacteroidales Krieg 2012
         1 Family Bacteroidaceae Pribram 1933 (Approved Lists 1980)
         2 Family "Rikenellaceae" Krieg et al., 2012 see Family Rikenellaceae Krieg et al. 2012
         3 Family "Porphyromonadaceae" nom. inval. see Family Porphyromonadaceae Krieg 2012
         4 Family "Prevotellaceae" Krieg, 2012 see Family Prevotellaceae Krieg 2012