Southern patas monkey

The southern patas monkey, Erythrocebus baumstarki, is a critically endangered Old World monkey found only in Tanzania and formerly in Kenya. It was described in 1905, later reduced to a subspecies of the common patas monkey, and restored as a distinct species by a 2017 review that the IUCN Red List and the American Society of Mammalogists followed. Adult males have a black face and nose. It lives in semi-arid acacia woodland dominated by whistling thorn, getting about half its food from the tree's gum and the rest from ants that live on it. The species once ranged across northern Tanzania and southern Kenya in two populations on either side of the Great Rift Valley, but by 2021 it survived only in the western Serengeti, with perhaps 100 to 200 animals. Farming, livestock, loss of water, snares and dogs drive the decline, and it may be Africa's most endangered primate.