Awwww, language coverage by the BBC. This time, it's putty-nosed monkeys in Nigeria. And the argument is that they are combining relatively few sounds in different ways to convey distinct meanings. These messages include systematic elements: who's talking, what they saw, and whether they "intend to travel".
The report's too sparse for me to say much more — how many sounds are we talking, and how systematically are they combined, etc. But don't monkeys recognize the voices of other monkeys in the group?
Hat tip to Elliott.