Pollen morphology of Malvaceae s.l. from Cerrado forest fragments: details of aperture and ornamentation in the pollen types definition

Abstract

We analyzed the pollen morphology of 13 Brazilian native species of Malvaceae s.l. from forest fragments of Cerrado belonging to nine genera [Bastardiopsis (K. Schum.) Hassl., Byttneria Loefl., Ceiba Mill., Eriotheca Schott & Endl., Guazuma Adans., Helicteres L., Heliocarpus L., Luehea Willd. and Pseudobombax Dugand] in search for characters that can expand the knowledge on the pollen morphology of species of the family that occur in areas of fragments. The pollen grains were acetolyzed, measured, described and photographed under light microscopy and scanning electron microscopy. The species studied were grouped into two pollen types based mainly on the type of aperture [simple aperture (3-porate or 4-colpate) and compound aperture (3-pororate or 3-colporate)], and the quantitative data were analyzed using descriptive and multivariate statistics. Details of apertures (planaperturate, angulaperturate, type of endoaperture, costa, aspis and atrium) and exine ornamentation (verrucate, microreticulate, microreticulate-echinate, reticulate and bireticulate) contributed as secondary data to the segregation of species in an artificial pollen key. The metric characters examined by multivariate analysis allow the distinction of groups of species, based on the length of the apertures and the diameters of the pollen grains. Our results allow the identification among genera and species of Malvaceae s.l. in Brazilian forest fragments.