So maybe Nupserha monticola Hintz?? However, in the description it not lack a lot of characters difficult to say more! In any case for me! It also exhibits characteristics of N bicoloripennis Breuning but this species is described from Ethiopia (Abyssinia) unlikely in Cameroon Buea especially! Buea has a very special wildlife in general rule in all cases that I have seen! If you have other pictures ? But I will see N monticole, nigerrima, rotkirchi ?? I will ask the typus .