According to the Colombian National Parks homepage, Colombia ranks third in the world for the most biologically diverse home to primates. In fact, it is home to 34 different species of primates, including 2 of the top 25 most endangered primates in the world. One is the Mico Tití, of which I wrote several months ago. You can read that post here: http://raisingcolombiankids.blogspot.com/2009/04/el-mico-titi.html
The other critically endangered species is the Varigated or Brown Spider Monkey (Ateles hybridus) called Mono Araña Marimba in Colombia. This species actually has 2 subspecies one of which is found exclusively in Colombia and the other sharing territory in Colombia and Venezuela.
This cutie is suffering from habitat loss, hunting, and an illegal pet trade. Because of habitat loss, only "9% of their potential range exists as continuous forest." You can see this monkey in several Colombian zoos, but they are in need of a captive breeding program. You can read more here: http://www.primate-sg.org/hybridus07.htm
If you are interested in learning more about Colombian primates, Thomas Richard Defler has written a field guide entitled: Primates of Colombia. The book illustrates and describes 28 of the 34 primate species of Colombia. You can own your own copy here: