Blue Nile patas monkey

The Blue Nile patas monkey (Erythrocebus poliophaeus), also called Heuglin's patas monkey, is an Old World monkey living along the Blue Nile valley in Ethiopia and Sudan, and possibly South Sudan. Heinrich Gottlieb Ludwig Reichenbach described it in 1862 from specimens collected by Theodor von Heuglin, but it was folded into the common patas monkey in 1927 and treated as a subspecies until a 2017 study by Spartaco Gippoliti restored it as a separate species. Its range is thought to lie between the Nile and the western escarpment of the Great Rift Valley. White hairs on the upper lip form a handlebar moustache, and it lacks the band between ear and eye seen in other members of its genus. Few specimens exist, suggesting it was never common; village resettlement, farming and the live animal trade threaten it, and it is listed as Data Deficient.