Estudos taxonômicos sobre Croton sect. Geiseleria (A. Gray) Baill. (Euphorbiaceae) no Brasil, com ênfase nas espécies ocorrentes na região Centro-Oeste

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Universidade Federal de Goiás


Euphorbiaceae Juss. comprises one of the most diverse lineages of phanerogams with 6300 species and 246 genera distributed mainly in the tropics, of which 949 and 64 occur in Brazil, where the family is represented in all biomes. Among its genera, Croton L. stands out by having a Pantropical distribution, have more than 1200 species, 300 of which are present in Brazil, and subdivided into 4 subgenera and 31 sections. Among the sections of the genus, C. sect. Geiseleria stands out as one of the three largest with 80 species distributed from the United States to Argentina, of which 50 are present in Brazil. Although Croton is the most studied genus of Euphorbiaceae in Brazil, species of Geiseleria are usually known only from their original descriptions or by scarce collections, many of them with mistaken identifications, besides having problems of typification and lack of illustrations. The objective of this study was to study the taxonomy of Croton sect. Geiseleria occurring in Brazil, with emphasis on those present in the Midwest region. The results are presented in seven chapters, drafted according to the norms of the journal where they were or will be published. The first relates to a taxonomic synopsis of the section Geiseleria for Brazil, in which 50 species are accepted, among which five are new to science (C. macrosepalus, C. ramosissimus, C. rhodotrichus, C. uliginosus and Croton sp. nov.) and four are transferred to the section (C. carinatus, C. catariae, C. spica and C. suavis) based on morphological characteristics and molecular data. In this manuscript are proposed 27 synonimizations, 75 lectotypes and a neotipification, as well as the reestablishment of C. aberrans and C. gracilescens, previously considered under C. hirtus and C. antisyphiliticus, respectively. The species of this article are contrasted in a key, commented on the geographical distribution, ecology, conservation status, morphological characterization, illustrated in their diagnostic characters and photographed. The second manuscript corresponds to the taxonomic treatment of the group for the Midwest region, where 32 species are recognized, of which five are new occurrences for the studied area (C. adenodontus, C. asperrimus, C. hadrianii, C. parodianus and C. sipaliwinensis). This manuscript has descriptions, comments about geographic distribution, ecology and morphological relationships, as well as illustrations, photographs and geographic distribution maps of the species. The chapters three to six deal with the descriptions of the new species, three of them already published and the last one submitted. The seventh manuscript is about the rediscovery of C. hadrianii, a species not recognized since 1873, but has here his complemented description, besides being first shown, photographed in nature, and commented about its distribution, flowering and fruiting, conservation status and morphological characterization.



SODRÉ, R. C. Estudos taxonômicos sobre Croton sect. Geiseleria (A. Gray) Baill. (Euphorbiaceae) no Brasil, com ênfase nas espécies ocorrentes na região Centro-Oeste. 2018. 378 f. Dissertação (Mestrado em Biodiversidade Vegetal) - Universidade Federal de Goiás, Goiânia, 2018.