RESUMEN
This study provides data on the past and present distribution of the red-bellied monkey, Cercopithecus erythrogaster erythrogaster, a subspecies that is endemic to Benin's southern ecosystems. The original distribution of this subspecies was between the Couffo River and the Nigerian border, but it has since been reduced to regions degraded by intense human settlement (such as the Oueme river valley) and to some better preserved areas, such as the Lama protected forest and some sacred grove forests in wet areas. Local people participated in this research programme and, as a result, many new localities have been discovered. All of these have been in wetlands in southern Benin, mainly in sacred groves. Conservation action for this subspecies will succeed only if local people are involved in its protection.