Abstract
Two new species of Rhynchospora sect. Tenues are described from savanna ecosystems in central South America. One of them, Rhynchospora chiquicerradensis, occurs in seasonally wet grasslands with sandy soils and on seepage slopes of the Cerrado domain, on sandstone outcrops with shallow soils and humid hillside seeps in the Chiquitano ecoregion of eastern Bolivia. The other, Rhynchospora nucistipitata, is restricted to humid grasslands and stream margins in the Cerrado domain of Brazil. The recognition of these taxa as distinct species is supported by detailed morphological analyses and by previously published phylogenetic evidence generated in earlier studies. A distribution map, preliminary conservation status assessments and images of the type specimens are also provided.
References
- Bachman, S., Moat, J., Hill, A., de la Torre, J. & Scott, B. (2011) Supporting red list threat assessments with GeoCAT: Geospatial conservation assessment tool. ZooKeys 150: 117–126. https://doi.org/10.3897/zookeys.150.2109
- Boeckeler, J.O. (1873) Die Cyperaceen des Königlichen Herbarium zu Berlin. Rhynchosporeae. Linnaea 37: 520–663.
- Cyperaceae Working Group (2025) Global Cyperaceae Database. Available from: https://www.cyperaceae.org (accessed 18 July 2025) https://doi.org/10.14284/681
- Goetghebeur, P. (1998) Cyperaceae. In: Kubitzki, K. (Ed.) The families and genera of vascular plants, 4. Springer, Berlin, pp. 164. https://doi.org/10.1007/978-3-662-03531-3_15
- Hofmann, G.S., Weber, E.J., Bastazini, V.A.G., Rossatto, D.R., Franco, A.C., Granada, C.E., Kaminski, L.A., Ubaid, F.K., Leandro-Silva, V., Borges-Martins, M., Silva, R.C., Cardoso, M.F., Oliveira, L.F.B., Aquino, F.E. & Pereira, M.J.R. (2025) Climate change in the Brazilian Cerrado: A looming threat to terrestrial biodiversity. Wiley Interdisciplinary Reviews: Climate Change 16: e70022. https://doi.org/10.1002/wcc.70022
- IUCN (2024) Guidelines for Using the IUCN Red List Categories and Criteria. Version 16. Prepared by the Standards and Petitions Committee. Available from: https://www.iucnredlist.org/resources/redlistguidelines (accessed 29 August 2025)
- Koyama, T. (1976) New Cyperaceae from tropical America. Bulletin of the National Science Museum, Tokyo. Series B, Botany 2 (4): 167–176.
- Kükenthal, G. (1950) Vorarbeiten zu einer Monographie der Rhynchosporoideae—Rhynchospora. Botanische Jahrbücher fur Systematik 75: 90–195.
- Kukkonen, I. (1994) Definition of descriptive terms for the Cyperaceae. Annales Botanici Fennici 31: 37–43.
- Kunth, C.S. (1837) Enumeratio Plantarum, Cyperographica Synoptica. Vol. 2. Stuttgart, Tubingen, pp. 274–303.
- Lucero, L.E. & Vegetti, A.C. (2012) Inflorescence structure in Rhynchospora Vahl (Cyperaceae). Flora 207: 47–56. https://doi.org/10.1016/j.flora.2011.10.003
- Naczi, R.F.C., Silva Filho, P.J.S., Strong, M.T. & Thomas, W.W. (2019) Rhynchospora belizensis (Cyperaceae), a new species of Rhynchospora section Tenues from Belize. Brittonia 72: 40–48. https://doi.org/10.1007/s12228-019-09597-6
- Nees von Esenbeck, C.G.D. (1842) Cyperaceae. In: Martius, C.F.P. (Ed.) Flora Brasiliensis 2 (1). pp. 110–147.
- Nunes, C.S., Silva Filho, P.J.S., Thomas, W.W. & Gil, A.S.B. (2019) Rhynchospora seccoi, a new species of Rhynchospora sect. Tenues (Cyperaceae) from Brazilian Amazon (Serra dos Carajás, Pará state). Phytotaxa 405: 91–100. https://doi.org/10.11646/phytotaxa.405.2.4
- Rocha, E.C., Sá, A.A.S. & Vale, V.S. (2025) The effect of habitat amount on species richness and composition of medium- and large-sized mammals in the Cerrado biome, Brazil. Diversity 17 (2): 83. https://doi.org/10.3390/d17020083
- Silva Filho, P.J.S. (2018) Estudo Taxonômico e Filogenético de Rhynchospora Vahl (Cyperaceae) Sect. Tenues. Ph.D. thesis. Porto Alegre: Universidade Federal do Rio Grande do Sul.
- Silva Filho, P.J.S., Thomas, W.W. & Boldrini, I.I. (2018) Two new species of Rhynchospora (Cyperaceae) from southern Brazil. Phytotaxa 383: 117–120. https://doi.org/10.11646/phytotaxa.383.1.8
- Silva Filho, P.J.S., Thomas, W.W. & Boldrini, I.I. (2019) Two new endemic species of Rhynchospora (Cyperaceae) section Tenues from Bahia, Brazil. Systematic Botany 44: 652–658. https://doi.org/10.1600/036364419X15620113920671
- Silva Filho, P.J.S., Thomas, W.W. & Boldrini, I.I. (2021) Redefining Rhynchospora section Tenues (Cyperaceae), a phylogenetic approach. Botanical Journal of the Linnean Society 196: 313–328. https://doi.org/10.1093/botlinnean/boab002
- Silva Filho, P.J.S., Weber, P. & Reginato, M. (2023) Rhynchospora waytii (Cyperaceae): A New Species with an Intriguing Disjunct Distribution in Brazil and Argentina. Systematic Botany 48 (4): 506–512. https://doi.org/10.1600/036364423X17000842213597
- Shorthouse, D.P. (2010) SimpleMappr, an online tool to produce publication-quality point maps. Available from: http://www.simplemappr.net (accessed 13 August 2025)
- Stearn, W.T. (1983) Botanical Latin revised. London and North Pomfret, Vermont: David & Charles, Newton Abbot.
- Strong, M.T. (2000) A new species of Rhynchospora section Tenues Kükenthal (Cyperaceae) from Puerto Rico. Brittonia 52 (3): 241–245. https://doi.org/10.2307/2666574
- Strong, M.T. (2005) Two new species of Rhynchospora sect. Tenues (Cyperaceae) from the Guianas, South America. Novon 479–483.
- Vahl, M. (1805) Enumeratio Plantarum vel ab aliis, vel ab ipso observatarum, cum earum differentiis specificis, synonymis selectis et descriptionibus succinctis. 2: 229. https://doi.org/10.5962/bhl.title.7564