Abstract
Caperonia (Acalyphoideae, Euphorbiaceae) is a monophyletic genus with 36 species naturally distributed in Latin America, Africa, and Madagascar. Its greatest diversity occurs in South America, where 28 species are found. Caperonia species are herbs or subshrubs that occur exclusively in open marshy environments. Here, we describe Caperonia itapevae, a new endangered species known from a single record from South Brazil, based on extensive morphological study and phylogenetic data.