Cercopithecus sp. (see comments)

Wolfs mona monkey? Doesn't have quite the right color pattern as far as I can see, but the face looks similar.

I think this is a Mona Monkey, but this species group is quite tough to identify.

@lintworm thanks for all the IDs, I really appreciate it. I'll update them on the computer later.
I might have additional photographs of this individual, are there any angles that might help with the ID or are they too difficult to distinguish morphologically?

@Dormitator A picture including the tail and a better picture of the head would help. It is either Mona's or Campbell's...

@lintworm alas, looks like I didn't get any other photographs of this species, sorry! Thanks for all the help, monkeys are not my thing and I didn't entirely trust ZTL...

@lintworm

Lowes is also a possibility, one would imagine.