Palynotaxonomy of Wissadula Medik. (Malvaceae: Malvoideae) in Brazil

Abstract

Abstract Malvaceae is divided into nine subfamilies, one of which is Malvoideae. WissadulaMedik., a genus within the Malvoideae, is divided into two sections according to mericarp morphology and the number of ovules per locule. Species belonging to the section Euwissadula have 3 or rarely 2 ovules, whereas species belonging to the section Wissada have a single ovule. In Brazil, 19 species are recorded under the two sections, including a single species (Wissadula stipulata Bovini) in section Euwissadula and 18 species in section Wissada. This study analyzed pollen grains from both sections of Wissadula with the aim of confirming or not the existence of these sections based on pollen morphology. All 19 taxa occurring in Brazil were analyzed. The botanical material was collected from exsiccatae deposited in national herbaria and subjected to the acetolysis method. Subsequently, slides were prepared, examined under light microscopy, and photomicrographed. Pollen grains are shed as monads, isopolar, large, suboblate, and triporate. The polar area is small in most species and large in a few others. The exine is thick, with echinate ornamentation, granules, and perforations. It was possible to distinguish the analyzed species on the basis of pollen diameters and spine characteristics (dimensions and distance). The findings showed that the pollen grains of species belonging to the two sections of Wissadulaare very similar in size, shape, aperture type, aperture number, and sexine ornamentation.