to stretch the spiral horn slam a bit far
add :

the western great Kudu : it lives in a pocket in the north of the CAR and south of Chad, 1000 km from the closest current great kudu .It looks like the usual kudu but its trophy cannot compete.The was a pocket in Sudan where roam the great kudu too, but knowing the atrocious reputation of the Sudaneses, I doubt they strive in Darfour.

Amongst the bushbucks, the western bushbuck is bearing a white harness on a reddish coat, the contrast is striking compared to the almost plain coat of the Limpopo's.
Let alone the almost black bushbuck in Ethiopia.

bongo : there is the western bongo living (theoritically from the Atlantic ocean in Liberia to west in the CAR. In fact mainly in CAR, Cameroon, Congos.
Another variety is the Kenyan bongo, now off limits for hunters but not for poachers.