The genus Selenomonas constitutes a group of motile crescent-shaped bacteria within the Veillonellaceae family and includes species living in the gastrointestinal tracts of animals, in particular the Ruminants. A number of smaller forms discovered with the light microscope are now in culture but many, especially the large selenomonads are not, owing to their fastidious and incompletely known growth requirements.

The genus Selenomonas constitutes a group of motile crescent-shaped bacteria within the Veillonellaceae family and includes species living in the gastrointestinal tracts of animals, in particular the Ruminants. A number of smaller forms discovered with the light microscope are now in culture but many, especially the large selenomonads are not, owing to their fastidious and incompletely known growth requirements.