Overview: The genus Prevotella is species-rich, with 51 species recognized in HOMD. Some of these species are found primarily in dental plaque and buccal mucosa, others primarily on the tongue, tonsils, hard palate, and throat.

Ecological role/importance in health and disease: As they are anaerobic, dental plaque Prevotella are more abundant in subgingival than supragingival plaque; major species include P. oris and P. nigrescens. On the tongue dorsum, P. melaninogenica has both high prevalence and high abundance, and an additional 5 or more Prevotella species also have >70% prevalence, making the tongue dorsum Prevotella community both abundant and complex. Two species, P. intermedia and P. nigrescens, are considered part of the "orange complex" in subgingival plaque marking part of the ecological succession from health toward periodontitis (Socransky et al. 1998).