Species endemism and species richness are complementary concepts usually used in biodiversity evaluation. They can be useful tools for efficiently defining conservation areas. In the present study, they are applied to the Brazilian Atlantic Forest, based on an orchid group endemic to this biome, the genus Baptistonia. The study of the species richness shows one very rich area (The Serra do Castelo, ES) and six rich areas. Three of these areas show an endemism index greater than 1. Eight areas, most important for biodiversity conservation, are proposed. Hierarchical relationships of endemism between nine phytogeographical areas are evaluated based on parsimony analysis of endemicity. This analysis confirms: (a) that two important endemism centers can be recognized in the southern ecological part of the Atlantic Forest, and (b) together with the phylogenetic relationships within the genus Baptistonia, that the Serra do Castelo appears to be the diversification center of the genus.