16S rRNA gene similarities indicate that Hallella seregens (Moore and Moore) and Mitsuokella dentalis (Haapsalo et al.) are genealogically highly related and are members of the genus Prevotella: emended description of the genus Prevotella (Shah and Collins) and description of Prevotella dentalis comb. nov.

Because of similarities in the cellular fatty acid compositions of Hallella seregens and Mitsuokella dentalis, we determined the 16S rRNA gene sequences of the type strains of these species to assess their relationship. A very high level of sequence relatedness (approximately 99.8%) was found between H. seregens and M. dentalis, indicating that these species are genealogically closely related. A comparative sequence analysis revealed that these two species are members of the genus Prevotella and are phylogenetically remote from Mitsuokella multiacidus (the type species of the genus Mitsuokella), which was found to be a member of the Sporomusa subbranch of the Clostridium subphylum of the gram-positive bacteria. On the basis of our phylogenetic findings, we propose that M. dentalis should be reclassified as Prevotella dentalis comb. nov.