(Pollen morphology of the tribe Protieae (Burseraceae) in South America). The tribe Protieae is represented in South America by the genera: Crepidospermum Hook. f., Protium Burm. f. and Tetragastris Gaertn. Crepidospermum comprises five species distributed mainly in Amazonia. Protium is a neotropical genus of approximately 146 species. Tetragastris is found almost exclusively in lowland moist forests in Central America, northern South America and parts of the Caribbean. Pollen grains from 177 collections representing 51 taxa were examined. The pollen material was acetolyzed, measured, described and photographed by light microcopy and, in most cases, also by electron microscopy scanning. The data obtained was statistically analysed by methods according the sample sizes. Pollen grains of Crepidospermum and Tetragastris are of the same intermediate size, being mostly subprolate with a triangular ambit, longicolpate, and psilate which indicates the stenopalynous nature of these genera. In Crepidospermum the species can be distinguished by the various characteristics of the apertures; the Tetragastris species studied are very similar in their pollen grains and were indistinguishable. Protium is diverse in the form of the pollen grains (spheric, prolate-spheroid, subprolate, prolate) and in the ornamentation of the exine (psilate, perforate, striate, micro-reticulate). Also as regards the polar diameter, the form and size of the endoaperture, the size of the colpus, the ornamentation of the colpus membrane, and the thickness of the exine, the studied species differed. These observations confirm that Protium is an euripalynous genus, in which, in most cases, the morphology of the pollen grain could support the taxonomic separation of species.
Burseraceae; Crepidospermum; Protium; Tetragastris; pollen grains
