Palynology of Huberia (Melastomataceae: Cambessedesieae): diversity and taxonomic implications

Abstract

Huberia DC. is a genus belonging to the family Melastomataceae, which comprises 37 species distributed in vegetation formations of the Amazon Forest and Andes complex and the Atlantic Forest biome. Recent phylogenetic studies have modified the circumscription of the genus to include the genera Behuria Cham. and Dolichoura Brade. Furthermore, the genus was placed in the new tribe Cambessedesieae, together with the genera Cambessedesia DC. and Merianthera Kuhlm. In view of the relevant contribution of palynology to taxonomic and phylogenetic studies, this study aimed to expand the palynological knowledge of Huberia. Samples from 22 species were obtained from specimens deposited in the herbaria of the Rio de Janeiro Botanical Garden (RB), National Museum/UFRJ (R), Municipal Botanical Museum of Curitiba (MBM), and Federal University of Paraná (UPCB). Flower buds were acetolysed and used to prepare pollen sediment slides. Slides were mounted with glycerinated gelatin and analyzed and photographed under a light microscope. The results showed pollen grains in monads, small, varying in shape from prolate-spheroidal to subprolate; heteroaperturate (colporate and pseudocolpate), tricolporate, with a small, very small, or non-existent polar area in syncolporate pollen; colpi long or very long and narrow, endoaperture lalongate with median constriction in most species and lolongate in others; exine perforate, rugulate, or striate microreticulate and the sexine thicker than the nexine. Based on the findings of this study, it is concluded that palynological characters provide information for the taxonomy of the group.