Rhynchospora section Pleurostachys (Cyperaceae): a phylogeny and three new species from the dry forests of Bahia and Espírito Santo, Brazil

Background and aims – We tested the integrity of Rhynchospora sect. Pleurostachys, understand its evolution and origins, and test the phylogenetic separation of three morphologically distinct taxa. Material and methods – We used the chloroplast marker trnL-F and the two nuclear markers nrETS and nrITS in our phylogenetic analysis. Key results – We demonstrated that R. sect. Pleurostachys is monophyletic and that the section is divided into two large clades with the early divergent species in each clade occurring outside the Atlantic Forest of Brazil. The molecular analysis also confirmed the distinctness of the three species new to science. Conclusions – Rhynchospora sect. Pleurostachys probably originated outside the Atlantic Forest but diversified there. The three taxa are described as species new to science: Rhynchospora barbosae, R. hamadryadis, and R. eremica, from the tropical semi-deciduous and deciduous forests of Bahia and Espírito Santo, Brazil, are illustrated and compared to other related species of the section.