Padrões de distribuição geográfica das espécies de Chamaecrista sect. Chamaecrista ser. Coriaceae (Benth.) H. S. Irwin & Barneby, Leguminosae - Caesalpinioideae

Abstract

An analysis of the geographic distribution of the 27 taxa belonging to 20 species of Chamaecrista sect. Chamaecrista ser. Coriaceae was carried out, based on maps depicting the known occurrences of the taxa. One species occurs in the Caribbean region, C. caribaea (Northr.) Britton, whereas the others are distributed in a main center of diversity, the Espinhaco Range, presenting two main patterns: 1) a continuous to disjunct occurrence through the Espinhaco Range and adjacent or disjunct areas, and 2) an endemic distribution in the southern region of that mountain range. Among the disjunctions, three species are noteworthy: one occurring in the Espinhaco and elevations of the Arco de Brasilia westwards Goias (C. cardiostegia H. S. Irwin & Barneby), other in the Espinhaco and in Espirito Santo State (C. mucronata (C. Sprengel) H. S. Irwin & Barneby), and a third one centered in the Espinhaco and in the Guyana Shield (C. roraimae (Benth.) Gleason). The distribution patterns are discussed, mainly as compared to data from other groups of angiosperms, and to a previous analysis of five species belonging to C. ser. Coriaceae. The results show a concentration of endemic species in highlands in the Cerrado Domain. They give additional support to the high degree of endemism already documented for other groups in the region. This analysis is an initial step allowing further studies to understand the processes responsible for the diversification of the group in the cerrado, specially in elevated areas.