Palinologia de espécies de Sapindales A. Juss. ex Bercht. & J. Presl (Magnoliophyta) de um fragmento urbano de Floresta Atlântica do sudeste do Brasil

Abstract

Sapindales include representatives with high economic potential and wide geographic distribution, for which there are taxonomic divergences and gaps in the knowledge of pollen morphology. Palynological studies previously carried out with some species of the order showed their importance in solving taxonomic problems and in the interpretation of phylogenetic relationships between species. The Atlantic Forest is home to a high number of Sapindales species for which palynological studies are still incipient. The Botanical Garden of the Federal University of Juiz de Fora is located in an urban fragment of the Atlantic Forest, in southeastern Brazil and has a high species richness, among which about 20 species of Sapindales from the families: Anacardiaceae R.Br., Burseraceae Kunth, Meliaceae A. Juss., Rutaceae A. Juss. and Sapindaceae A. Juss. Thus, the present work aims to study the morphology of pollen grains of Sapindales species that occur in the Botanical Garden of the Federal University of Juiz de Fora, to evaluate the relevance of palynological attributes for the expansion of taxonomic and ecological information of these species and, provide data for the elaboration of the Palynological Catalog of the Botanical Garden of the Federal University of Juiz de Fora. To carry out the study, heerborized botanical material available in the collection of the Herbarium Leopoldo Krieger was used. The observations were carried out using light microscope and scanning electron microscope, according to standardized methodologies for palynological studies. The results demonstrate that the pollen morphology of the order Sapindales is quite varied and can be described as medium, rarely small, isopolar or weakly heteropolar, radially symmetrical, tri-apertured pollen grains but, also, presenting some variation from four to six apertures. The Anacardiaceae family have medium pollen grains ranging from reticulate to striate and may present both types of ornamentation in the same pollen grain. Burseraceae include pollen grains ranging from small to medium and psilate exine. Meliaceae exhibit medium-sized pollen grains and psilate ornamentation, with the greatest variation within the groups studied, regarding the shape and type of apertures, which can be syncolporate, parasyncolporate and colporate. It is worth mentioning the presence of orbicules associated to the pollen grains of the species of the genus Cedrela, which helped in the differentiation of the species and in the elaboration of ecological inferences about the pollination of the species of this genus. Rutaceae present medium to small sized pollen grains, with heterobrochate reticules. The pollen grains of Sapindaceae species were characterized by their weakly heteropolarity, medium size, microreticulate ornamentation and amb ranging from subtriangular to triangular.