Systematics of the family Euphorbiaceae s.s. in the neotropics: tribes Hippomaneae and Crotoneae

Abstract

The family Euphorbiaceae s.s. is one of the largest, most diverse, and complex of the Angiosperms, the largest of the Order Malpiguiales, with 246 genera and around 6300 species. The large number of species in almost all kind of vegetation in the neotropics, together with the great morphological variability of the species, make the family a taxonomic challenge. The tribes Hippomaneae and Crotoneae include more than half of the species of Euphorbiaceae s.s. found in Brazil. From the 33 genera of Hippomaneae, 13 are found in Brazil, some of them with their limits not well resolved. Microstachys, on the other hand, is one of the most morphologically distinct genera in the tribe, but despite this, several of its species were originally described or treated in different genera, like Sebastiania and Stilligia. It has 15 species of subshrubs, mostly in South America, 11 very common in cerrados and campos rupestres in Brazil, one in Asia and Oceania and about four in Africa. Of seven genera of the tribe Crotoneae, five occur in Brazil, including Astraea, recently segregated from Croton, with approximately 10 species of subshrubs or schrubs, all found in Brazil, in edges of riparian forests, campos rupestres, caatinga and cerrados. Considering the high representation of these genera and the taxonomic problems we detected in the development of our studies in the family Euphorbiaceae s.s. in Brazil, we decided to perform the taxomic revision of both, based on morphological and molecular data from ITS, matK, rbcL, ndhF, trnH-psbA, trnL-F regions, in order to infer phylogenies using as external groups the other representatives of their tribes. (AU)