“…On the basis of these studies Shah and Collins (33)(34)(35) proposed that the genus Bacteroides be divided into three major groups: (i) a redefined genus Bacteroides, restricted to members of the B. fiagilis group; (ii) genus Prevotella, consisting of moderately saccharolytic, bile-sensitive, predominantly oral species, such as P. rnelaninogenica; and (iii) genus Porphyromonas, for the pigmented species P. asaccharolytica and close relatives. A number of predominantly monospecific genera (e.g., Anaerorhabdus [32], Catonella [21], Dialister [21], Fibrobacter [20], Hallella [21], Johnsonella [21], Megamonas [28], Mitsuokella [29], Oribaculum [ 211, Rikenella [4], Ruminobacter [40], Sebaldella (31), and Tissierella [3]) have been described for some of the species that do not conform to the description of these three genera. The species B. levii (formerly B. melaninogenicus subspecies levii) (10,11) was excluded from the genus Bacteroides as redefined by Shah and Collins (34), and its taxonomic position is currently incertae sedis.…”