Selenomonas ruminantium

Curved bacteria, usually crescent-shaped rods, with ends often tapered, occurring singly, in pairs, or short chains. They are non-encapsulated, non-sporing, motile, and ferment glucose. Selenomonas are found mainly in the human buccal cavity, the rumen of herbivores, and the cecum of pigs and several rodents. (From Bergey's Manual of Determinative Bacteriology, 9th ed)