Taxonomy, palynology, and seed morphology of Paepalanthus decumbens, a new species of Eriocaulaceae from Minas Gerais, Brazil

Background and aims – Paepalanthus is the largest genus of Neotropical Eriocaulaceae and the largest genus of Brazilian monocots. Much of its taxonomic and morphological diversity remains unknown. A new species is described, with details on pollen and seed morphology.Methods – The morphological description of the vegetative and floral characters was made using a stereoscopic microscope with camera. Pollen and seed samples from the new species and from two related taxa were studied under light microscopy and scanning electron microscopy.Key results – Paepalanthus decumbens is described and illustrated, including details of pollen grains and seeds. The species is restricted to a small area in the campos rupestres of Serra de São José (Minas Gerais, Brazil), and therefore should be considered as critically endangered. The decumbent stem, falciform leaves with long trichomes along the margins, the numerous and sericeous scapes of roughly the same size of the leaves, and the dark castaneous involucral bracts are useful features for the recognition of the new species. Paepalanthus decumbens is placed in P. subsect. Polyactis and compared with P. microphyllus and P. stannardii, which have their pollen grains and seeds also herein described for the first time.