Rhynchospora Vahl (1805:229) is the richest genus of Cyperaceae in southern Brazil (66 spp., Flora do Brasil 2020). Most species grow in open areas such as meadows and grasslands but some occur in forests or along forest edges. As part of a taxonomic and phylogenetic study of the related sections Luzuliformes Kük. (1950:183) and Tenues Kük. (1950:186), we revised specimens in the herbaria of the New York Botanical Garden (NY) and the United States National Herbarium (US). We found specimens of two new species from the states of Santa Catarina and Paraná in southern Brazil and sought additional specimens of these species in the principal herbaria of southern Brazil (FLOR, HBR, ICN, MBM). These two species clearly belong to sections Tenues and Luzuliformes, which were last revised by Rocha and Luceño (2002) and Silva Filho et al. (2017). Both species are here described, compared to related species (Table 1), and illustrated (Figures 1 and 2).