The genus Piptadenia Benth.: pollen morphology and taxonomic implications

The genus Piptadenia Benth. has undergone several changes in its circumscriptions throughout its history, given the difficulty of its phylogenetic placement. Considering that palynological contributions have been significant for differentiating taxa within the Mimoseae tribe , the present study aims to characterize the representatives of the genus as well as describe the pollen grains of some taxa still unpublished in the literature. Three types of pollen grains were identified based on the number of grains per polyad considering the number of pollen grains and their ornamentation. However, other palynological characters are similar among species, supporting the monophyly of the genus. All species showed similarities, especially regarding size and shape, varying mainly in the number of pollen grains composing the polyads (8, 12, and 16). This variation has already been confirmed by morphological and molecular data. This study presents unprecedented palynological characterization of the species: Piptadenia affinis, P. cuzcoënsis, P. gonoacantha, P. imatacae, P. killipii, P. micracantha, and P. robusta.

Keywords:
diversity; exine; genus; morphology; palynotaxonomy; Piptadenia Benth; pollens; taxonomic