Daniela Santos Carneiro-Torres

An overview of recent taxonomic studies on Euphorbiaceae s.l. in Brazil

As Euphorbiaceae sensu lato distribuem-se especialmente nos tropicos, nos mais variados tipos de vegetacao e habitats, sendo uma das maiores, mais complexas e diversificadas familias das Angiospermas. Foi recentemente dividida em quatro familias e segundo os atuais sistemas de classificacao, baseados em estudos filogeneticos envolvendo dados moleculares, esta assim classificada: Euphorbiaceae sensu stricto, Phyllanthaceae, Putranjivaceae e Picrodendraceae, havendo uma proposicao de estabelecer Peraceae, taxon ainda em discussao. Houve tambem mudancas no posicionamento taxonomico de generos de ampla distribuicao no territorio brasileiro, tais como Amanoa, Drypetes, Pera, Phyllanthus, Podocalyx, Pogonophora e Richeria, entre outros. Alem disso, novas especies vem sendo propostas e a amplitude dos limites de distribuicao de diversos taxons vem aumentando no Brasil. Diante do exposto, os autores fornecem um panorama geral dos estudos mais recentes e avancos na taxonomia de Euphorbiaceae s.l. nas regioes Norte, Nordeste, Sudeste e Sul do pais, concentrando-se nos trabalhos de revisao e floras regionais, bem como nas mudancas que resultaram em nova configuracao taxonomica da familia.

Three new species of Croton (Euphorbiaceae s.s.) from the Brazilian Caatinga

While conducting a floristic inventory of Croton from the Brazilian Caatinga, three new species were discovered. Croton arenosus, Croton glandulosobracteatus, and Croton harleyi are described and illustrated here. Based on morphological characters, Croton glandulosobracteatus is proposed to belong to section Barhamia, and C. arenosus and C. harleyi to section Geiseleria.

Further Support for the Crotoneae Phylogeny: A New Species of Brasiliocroton (Euphorbiaceae) Based on Morphological, Geographical, and Molecular Evidence

Abstract Brasiliocroton muricatus is a new species from eastern Brazil that is described, illustrated, and placed in a phylogenetic context. It is only the second known species of Brasiliocroton. Its phylogenetic position was inferred based on sequences from the nrITS and plastid trnL-F markers, using a sampling of closely related genera in tribe Crotoneae. Brasiliocroton muricatus was recovered within tribe Crotoneae, forming a clade with B. mamoninha. This clade is in turn sister to the large genus Croton, giving additional support to previous phylogenetic studies including B. mamoninha. The most obvious morphological characters distinguishing the new species from B. mamoninha are the unisexual, axillary inflorescences and the smaller fruits with muricate surface and white, stellate trichomes, as opposed to bisexual, terminal inflorescences and bigger fruits with smooth surface and ochraceous to brown dendritic trichomes in B. mamoninha. Both species of Brasiliocroton have the filaments of the staminate flowers erect in bud, which is the main character state distinguishing them from the closely related Croton and Astraea. Additional morphological features distinguishing Brasiliocroton and Croton from the rest of tribe Crotoneae are also discussed.

Pollen morphology of the Acalyphoideae and Euphorbioideae (Euphorbiaceae) of the Caatinga ecoregion in Brazil

This study dealt with six species of Acalyphoideae and 18 species of Euphorbioideae occurring in the Caatinga ecoregion, with emphasis on endemic species. Pollen samples were obtained from herbarium specimens and were acetolysed and analysed via light and scanning electron microscopy. The pollen of three genera of Acalyphoideae was medium to large, 3-colporate or 3-colpate, with an echinate-perforate exine that was reticulate, bireticulate, and microreticulate. The six genera of Euphorbioideae studied exhibited pollen grains that were small, medium and large; 3-colporate with margines; and an exine with microreticulate, microreticulate-rugulate, microreticulate-caveate, and reticulate ornamentation. The pollen characteristics were more variable in the Acalyphoideae compared to the relatively homogeneous Euphorbioideae. This study provides new data and interpretations of the pollen morphology of two subfamilies of the Euphorbiaceae of the Caatinga ecoregion in Brazil.

Pollen morphology of Crotonoideae (Euphorbiaceae) from Seasonally Dry Tropical Forests, Northeastern Brazil

Crotonoideae is a subfamily of Euphorbiaceae, a plant family that is characterized by the presence of laticifers and pollen grains with Croton pattern exine. We analysed 48 species of Crotonoideae from Seasonally Dry Tropical Forests within Caatinga vegetation aiming to contribute to the pollen morphology of this subfamily, focusing on endemics to these forests. Pollen samples were obtained from specimens of the herbarium. Pollen grains were acetolyzed, measured, photographed and described using light and scanning electron microscopy methods. Three pollen types and seven subtypes were recognized based on aperture type, polarity, shape, size and details of the exine sculpture. The exine ornamentation and the type and number of apertures are the most important characteristics for recognizing genera in Crotonoideae. Inaperturate pollen grains with surface pila plicate were observed in representatives of Croton and Jatropha; 4–8 pantoporate pollen grains and a 3-colpate one with psilate pila were observed in Cnidoscolus, and 10–22 pantoporate pollen grains with rugulate pila were observed in Manihot. Due to the high diversity of Crotonoideae pollen morphology, we highlighted its eurypalynous properties, in addition to its taxonomic relevance, for the identification of groups.