Abstract
A new species, Rhamnidium riograndense, from southern Brazil, is here described and illustrated. We present information about its distribution, habitat, phenology, conservation status and a key for all the South American species of the genus is provided. The new species is endemic to the central part of the state of Rio Grande do Sul, in the transition between Paraná and Pampean provinces in rocky habitats, mostly mountain slopes, where only four populations are currently known.
References
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<p>Silveira, F.S., Bordignon, S.A.L. & Miotto, S.T.S. (2019) <em>Mimosa cerifera</em>, a New Threatened Species from the Pampa Biome, Southern Brazil. <em>Systematic Botany</em> 44: 133–138. https://doi.org/10.1600/036364419X697976</p>
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<p>Spegazzini, C.L. (1923) Breves notas cactológicas. <em>Anales de la Sociedad Científica Argentina</em> 96: 61–75.</p>
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<p>Thunberg, C.P. (1781) <em>Nova Genera Plantarum</em>. Vol. 1. J. Edman, Upsala, 28 pp.</p>
<p>Bastos, N. R. (1990) A família Rhamnaceae R. Br. no Rio Grande do Sul. Gêneros: <em>Colubrina</em> Rich. ex Brongn., <em>Gouania</em> Jacq. e <em>Hovenia</em> Thunb. <em>Pesquisas, Botânica</em> 41: 99–122.</p>
<p>Beentje, H.J. (2010) <em>The Kew Plant Glossary – an illustrated dictionary of plant terms</em>. Royal Botanic Gardens, Kew, 160 pp.</p>
<p>Büneker, H.M., Pontes, R.C., Soares, K.P., Witeck-Neto, L. & Longhi, S.J. (2013) Uma nova espécie reófita de <em>Dyckia</em> (Bromeliaceae, Pitcairnioideae) para a flora do Rio Grande do Sul, Brasil. <em>Revista Brasileira de Biociências </em>11: 284–289. Available from: http://www.ufrgs.br/seerbio/ojs/index.php/rbb/article/view/2454 (accessed 1 July 2021)</p>
<p>Büneker, H.M., Ferrarese, M.D. & Canto-Dorow, T.S. (2017) <em>Tradescantia multibracteata</em>, a new species of Commelinaceae from Rio Grande do Sul, Brazil. <em>Phytotaxa</em> 308: 89–96. https://doi.org/10.11646/phytotaxa.308.1.7</p>
<p>Büneker, H.M., Soares, K.P., Assis, L.C. & Witeck-Neto, L. (2018) Taxonomic novelties in Southern Brazilian Amaryllidaceae – III: <em>Hippeastrum multiflorum</em>, a new species from Rio Grande do Sul. <em>Balduínia</em> 64: 34–41. https://doi.org/10.5902/2358198035736</p>
<p>Coelho, G.P. & Miotto, S.T.S. (2017) New Species of <em>Buddleja </em>(Scrophulariaceae) from Southern Brazil. <em>Systematic Botany</em> 42: 968–97. https://doi.org/10.1600/036364417X696591</p>
<p>Chodat, R. & Hassler, E. (1903) Plantae Hasslerianae soit énumération des plantes récolétees au Paraguay par le Dr. Emile Hassler, d’Aarau (Suisse), de 1885 à 1902. <em>Bulletin de l’Herbier Boissier</em> 3: 50–63.</p>
<p>CRIA (Centro de Referência e Informação Ambiental) (2011)<em> Specieslink - simple search</em>. Available from: http://www.splink.org.br/ (accessed June 2020)</p>
<p>Cusato, L.I. & Tortosa, R.D. (2013) Rhamnaceae.<em> In: </em>Ramella, L. & Perret, P. (Eds.) <em>Flora del Paraguay</em> <em>44</em>. Conservatoire et Jardin botaniques, Ville de Genève, Genève, 63 pp.</p>
<p>Ellis, B., Daly, D.C., Hickey, L.J., Johnson, K.R., Mitchell, J.D., Wilf, P. & Wing, S.L. (2009) <em>Manual of leaf architecture</em>. New York Botanical Garden, New York, 190 pp.</p>
<p>Gasper, A.L., Stehmann, J.R., Roque, N., Bigio, N.C., Sartori, Â.L.B. & Grittz, G.S. (2020) Brazilian herbaria: an overview. <em>Acta Botanica Brasilica</em> 34: 352–359. https://doi.org/10.1590/0102-33062019abb0390</p>
<p>GBIF.org (2020) <em>GBIF Home Page</em>. Available from: https://www.gbif.org (accessed February 2020)</p>
<p>Gonçalves, E.G. & Lorenzi, H. (2007) <em>Morfologia vegetal: organografia e dicionário ilustrado de morfologia das plantas vasculares</em>. Instituto Plantarum de Estudos da Flora, São Paulo. 446 pp.</p>
<p>Hauenschild, F., Matuszak, S., Muellner-Riehl, A.N. & Favre, A. (2016) Phylogenetic relationships within the cosmopolitan buckthorn family (Rhamnaceae) support the resurrection of <em>Sarcomphalus</em> and the description of <em>Pseudoziziphus</em> gen. nov. <em>Taxon</em> 65: 47–64. https://doi.org/10.12705/651.4</p>
<p>IUCN (2019) <em>Guidelines for Using the IUCN Red List Categories and Criteria</em>, Version 14. Prepared by the Standards and Petitions Committee, 113 pp. Available from: http://www.iucnredlist.org/documents/RedListGuidelines.pdf (accessed June 2020)</p>
<p>Jussieu, A.L. (1789) <em>Genera plantarum</em>. Herissant, Paris, 498 pp.</p>
<p>Landrum, L.R. (2016) A revision of the <em>Psidium salutare</em> complex (Myrtaceae). <em>Sida</em> 20: 1449–1469.</p>
<p>Lima, R.B. (2000) <em>A família Rhamnaceae no Brasil, diversidade e taxonomia</em>. Tese de Doutorado, Universidade de São Paulo, São Paulo, 292 pp.</p>
<p>Lima, R.B. [in memoriam], Barbosa, M.R.V. & Giulietti, A.M. (2020) Rhamnaceae in Flora do Brasil 2020. Jardim Botânico do Rio de Janeiro. Available from: http://floradobrasil.jbrj.gov.br/reflora/floradobrasil/FB207 (accessed April 2021)</p>
<p>Menezes, L.C. (2009) Uma nova espécie do Rio Grande do Sul: <em>Cyrtopodium witeckii</em>. <em>Boletim CAOB</em> 75: 58–63.</p>
<p>Morrone, J.J. (2014) Biogeographical regionalisation of Neotropical region. <em>Zootaxa</em> 3782: 1–110. http://dx.doi.org/10.11646/zootaxa.3782.1.1</p>
<p>QGIS Development Team (2020) QGIS Geographic Information System. Open Source Geospatial Foundation Project. Available from: http://qgis.org (accessed May 2020)</p>
<p>Reflora - Herbário Virtual (2020) <em>Herbário Virtual Reflora</em>. Jardim Botânico do Rio de Janeiro, Rio de Janeiro. Available from: http://reflora.jbrj.gov.br/reflora/herbarioVirtual (accessed 25 February 2020)</p>
<p>Reissek, S. (1861) Rhamneae.<em> In: </em>Martius, C.F.P. & Eichler, A.G. (Eds.) <em>Flora brasiliensis 11</em>. Frid. Fleischer, Lipsiae, pp. 81–116.</p>
<p>Richardson, J.E., Fay, M.F., Cronk, Q.B., Bowman, D., Chase, M.W. (2000) A phylogenetic analysis of Rhamnaceae using rbcl andt rnl-f plastid dna sequences. <em>American Journal of Botany</em> 87: 1309–1324. http://dx.doi.org/10.2307/2656724</p>
<p>Schultes, J.A. & Schultes, J.H. (1830) Classis VL, Hexandria.<em> In: </em>Roemer, J.J. & Schultes, J.A. (Eds.) <em>Systema Vegetabilium.</em> Vol. 7. Pt. 2. pp. 45–107.</p>
<p>Silveira, F.S., Bordignon, S.A.L. & Miotto, S.T.S. (2019) <em>Mimosa cerifera</em>, a New Threatened Species from the Pampa Biome, Southern Brazil. <em>Systematic Botany</em> 44: 133–138. https://doi.org/10.1600/036364419X697976</p>
<p>Soares, K.P. & Longhi, S.J. (2011) Uma nova espécie de <em>Butia</em> (Becc.) Becc. (Arecaceae) para o Rio Grande do Sul. <em>Ciência Florestal</em> 21: 203–208. https://doi.org/10.5902/198050983223</p>
<p>Spegazzini, C.L. (1923) Breves notas cactológicas. <em>Anales de la Sociedad Científica Argentina</em> 96: 61–75.</p>
<p>Stehmann, J.R. & Semir, J. (2005) New species of <em>Calibrachoa</em> and <em>Petunia</em> (Solanaceae) from subtropical South America.<em> In: </em>Keating, R.C., Croat, T.B. & Hollowell, V.C. (Eds.) <em>A Festschrift for William G. D’Arcy The Legacy of a Taxonomist</em>. Missouri Botanical Garden Press, Saint Louis, pp. 341–348.</p>
<p>Thiers, B. [continuously updated] <em>Index Herbariorum: A global directory of public herbaria and associated staff</em>. New York Botanical Garden’s Virtual Herbarium. Available from: http://sweetgum.nybg.org/science/ih/ (accessed April 2019)</p>
<p>Thunberg, C.P. (1781) <em>Nova Genera Plantarum</em>. Vol. 1. J. Edman, Upsala, 28 pp.</p>