Abstract— Mimosa is a species-rich genus with about 600 species distributed mainly in the Neotropics. Mimosa is especially diverse in the Cerrado where the genus shows high levels of endemism, but it is also represented in the Caatinga (the Brazilian seasonally dry vegetations). Four new species are described here, M. emaensis and M. sevilhae from the Cerrado, M. afranioi from the Caatinga, and M. robsonii from the Atlantic domain. We assessed their informal conservation status and two species would likely be categorized as Endangered (EN), one as Vulnerable (VU) to extinction, and one as Data Deficient (DD).