New circumscription, morphology and synopsis of Chamaecrista sect. Chamaecrista ser. Coriaceae (Leguminosae)

A new circumscription of Chamaecrista sect. Chamaecrista ser. Coriaceae is presented based on the results of molecular and morphological analyses. The series is monophyletic upon exclusion of three species that were included within it by Irwin and Barneby. Morphological variation within the series is discussed. Characters previously neglected, such as the detailed morphology of extrafloral nectaries and the position of stamens, are shown to be valuable for taxonomic purposes. The synopsis includes three neotypifications ( C. cinerascens, C. mucronata, C. rotundata var. grandistipula ), two new synonymizations ( C. papillata under C. arrojadoana , and C. rotundata var. grandistipula under C. rotundata var. rotundata ), and a new combination ( C. arrojadoana ). A key for identification of the species, lists of specimens analysed, notes on taxonomy, nomenclature, and geographic distribution of the taxa, as well as illustrations of diagnostic characters are presented. In the new circumscription, the series comprises nineteen species, two of them each further divided into two varieties, to give a total of 21 taxa, distributed mainly in the Brazilian Central Plateau.