Abstract

This work presents a new circumscription and a taxonomic treatment for Chamaecrista ser. Setosae that resulted from previous phylogenetic studies and the analysis of ca. 350 collections, including typus, as well as the observation of populations in field. Nine species were recognized for the series, eight of which are endemic to Brazil, and one firstly recorded for the country (Ch. orenocensis). Are proposed the synonymizations of all varieties of Ch. setosa, the transfer of Ch. amphibola from the Setosae series to the ser. Ursinae and its consequent synonymization under Ch. exsudans, and the inclusion of Ch. multiseta from the Absoideae series to the ser.  Setosae based on previous phylogenetic and morphological evidences. Species are contrasted in a key, with their updated typifications, represented through images and described and commented on their flowering and fruiting periods, their geographical distributions, including, maps, preferred environments and conservation status, morphological relationships, as well as illustrated by their diagnostic characters.