I wanted to have a lemur familiar. I figured: stats as a monkey, +2 to Reflex saves for a bonus? Sound about right? [I can't recall if a lemur was mentioned in any sourcebook.]
I would say to use the Monkey stats for basically any small primate. You may want to adjust climb speeds or make other little tweaks to add flavor or to make it more like whatever monkey you're specifically thinking of, but the base stats work well.
