Scarabaeoidea is one of the biogeographically best known groups of organisms for Nuclear Central America, especially Guatemala. They have been used to determine areas of endemism for cloud forests of the region and to analyze relationships among these endemic areas. A major north-south division of these areas is described. Lowland scenarios are also given. This information was used for justifying the establishment of biological reserves in the area and is a tool available for prioritization of reserve establishment that could be adapted to other parts of the world as well.