Estudo taxonômico sobre o gênero Actinostemon Mart. ex klotzsch (Hippomaneae - Euphorbiaceae) no Brasil

Abstract

Actinostemon presents a specific controversial composition, ranging from 13 to 30 neotropical species, distributed from Cuba to Uruguay, with the main center of taxonomic diversity in Brazil. The genus presents a complex morphology and since its establishment goes through changes in its area, being accepted by some authors or included in the synonymy of Gymnanthes by others. Motivated by the controversial and problematic specific taxonomic representation, Actinostemon contemplated in this thesis which aimed to carry out a taxonomic study for species occurring in Brazil. The objectives of this study were to identify and update the morphology and geographic distribution of Brazilian species of Actinostemon. For the taxonomic study, were analyzed, collected in the field specimens and herbalized specimens (about 550 herbarium specimens) from 33 herbariums, mostly Brazilian. The species identification were done through specialized literature, protologos and analysis of photographs of such collections. Were found seven species A. amazonicus Pax & K. Hoffm., A. appendiculatus Jabl., A. concolor (Spreng.) Müll. Arg., A. echinatus Müll. Arg., A. klotzschii (Didr.) Pax, A. schomburgkii (Klotzsch) Hochr. and A. verticillatus (Klotzsch) Baill. Two well-recognized species in Brazil, A. concepcionis and A. lundianus, were accepted as synonyms of A. klotzschii. In Brazil, Actinostemon occurs in the Amazon (A. amazonicus, A. concolor and A. schomburgkii), Caatinga (A. concolor and A. klotzschii) in the Cerrado (A. concolor and A. klotzschii), and the Atlantic Forest (A. appendiculatus, A. concolor, A. echinatus, A. klotzschii and A. verticillatus). A. appendiculatus, A. echinatus and A. verticillatus are endemic of Brazil. The taxonomic treatment includes an identification key, descriptions, list of material examined, data distribution and phenology, and illustrations of the species.