Pollen morphology ofCupheaP.Browne sectionTrispermumKoehne (Lythraceae): implications for the new section circumscription

CupheasectionTrispermum, one of the 13 sections of the genus, predominantly composed of Brazilian species, underwent a new circumscription after morphological and molecular studies. The pollen morphology of classic representatives of the section and related taxa transferred to this section was investigated, based on light microscopy and scanning electron microscopy, to support the taxonomy and the new section circumscription. The analyzed species present pollen that is small to medium in size, isopolar, oblate, triangular to ovate-triangular, tricolporate, and syncolpate, with prominent pores and psilate exine, thickened between the pores in the mesocolpium. The results of this study confirm the palynological homogeneity ofC. sect.Trispermum, and of the taxa transferred from other sections, which are unified by exine thickening in the region between the pores. These characteristics corroborate the monophyly of the section, according to molecular phylogenetic studies.