A new species of the genus Besleria (Gesneriaceae), endemic to the department of Cauca, Colombia, is described and illustrated here. The new species, Besleria santaclarensis Clavijo & Sánchez-Taborda, was discovered in the Regional Protective Forest Reserve “Serranía El Pinche”, Cordillera Occidental of the Colombian Andes. B. santaclarensis is distinguished by the epedunculate inflorescences, usually in the leafless axils near the base, with up to eight orange flowers, and by the magenta calyx that covers 2/3 of the corolla.

Una nueva especie del género Besleria (Gesneriaceae), endémica del departamento del Cauca, Colombia, se describe e ilustra aquí. La nueva especie, Besleria santaclarensis Clavijo & Sánchez-Taborda, se descubrió en la Reserva Forestal Protectora Regional “Serranía El Pinche”, Cordillera Occidental de los Andes colombianos. B. santaclarensis se distingue por las inflorescencias epedunculadas, usualmente en las axilas de nudos sin hojas ubicados hacia la base, con hasta ocho flores anaranjadas por inflorescencia y cáliz magenta que cubre 2/3 de la corola.

Andes, Cauca, Choco biogeographic, Protective Forest Reserve, San Juan de Micay, taxonomy

Besleria Plum. ex L. includes 160 species (Clark et al. 2020) of terrestrial herbs, shrubs and small trees that grow in the rainforest understory. It is strongly supported as monophyletic in the tribe Beslerieae (Smith 2000; Roalson and Clark 2006; Clark et al. 2010). Biogeographic analyses of the family suggest that it diversified in the Andes 15 Mya (Perret et al. 2013; Roalson and Roberts 2016). Besleria is one of the largest and least known genera among the New World Gesneriaceae; it occurs in most Neotropical rainforests with the highest diversity in the tropical Andes (>100 species), followed by Central America (20 species) (Skog and Boggan 2007; Ferreira et al. 2016). Colombia is the country with the highest diversity of Besleria, with more than 80 species (Cortés 2013), followed by Peru with 35 (Kvist et al. 2005), Ecuador with about 20 (Skog and Kvist 1997) and Panama with 15 (Skog 1978). In Colombia, most of the species are found in the humid forests of the Andes and the Choco Biogeographic region, whereas few species grow in the Amazon (Cortés et al. 2017). In the Andes, the largest number of species is found in the Cordillera Occidental of Colombia. For example, Besleria is the third largest Gesneriaceae genus with 10 species out of the 96 recorded in northern Valle del Cauca (Clavijo et al. 2014). Likewise, Pedraza and Betancur (2015) recorded five species of Besleria out of the 70 Gesneriaceae species collected in the National Natural Park Orquídeas (Antioquia), north of the Cordillera Occidental.

The Serranía El Pinche in Argelia (Cauca) is located in the southern portion of the Cordillera Occidental of the Colombian Andes, and is part of the Munchique-Pinche corridor, a region known for high levels of biodiversity (Paz-B et al. 2018). Biogeographically, the Serranía El Pinche is more similar to the Nudo de los Pastos and the Colombian Massif than to the northern portions of the Cordillera, mainly due to the lower elevation Paramos on the Pacific slopes (Becking 1995). For the first settlers of the Serranía, the conservation of native ecosystems and sustainable rural development were paramount in this biodiverse region. Early settlers inspired in their children the importance of preserving their natural resources by creating alliances that would allow the proper management and establishment of a formal protected area. As a result of this initiative, the Regional Protective Forest Reserve “Serranía El Pinche” was created in 2008. The Reserve is part of the San Juan de Micay river basin that ranges in elevation from 1040 to 3744 meters above sea level; it has 7,256 ha, however, after its expansion it will have in total 11,930 ha. 90.4% of the reserve corresponds to primary forests and 9.6% to perturbed forests, crops and pastures. The Reserve “Serranía El Pinche” and the buffer zone include 913 households (Paz-B et al. 2018).

The upper San Juan de Micay river basin is a unique biodiverse area in the Pacific slopes of the Andes that still has large extensions of primary tropical rainforests (Becking 1995), despite high deforestation rates caused by agriculture and the presence of illicit crops. The preservation of protected areas led by local communities in regions suffering rapid deforestation is essential to conserve species and entire ecosystems. In fact, private and community-owned protected areas have been successful in preserving natural ecosystems in the northern Andes, where biological diversity is high (Joppa et al. 2008; Armenteras et al. 2009; Rodríguez et al. 2013). Therefore, following the legacy of the first naturalists and ecologists that explored La Serranía El Pinche, we aim to contribute to the floristic knowledge of this underexplored rainforest in southwestern Colombia. The plant inventory and discovery of new taxa in this region will provide important information to support the future expansion of the Reserve toward the coast, in the municipalities of Guapi and Timbiquí, achieving a broad elevation coverage from the Pacific coast to the paramos of the Andean highlands.

During a rapid ecological evaluation carried out in September of 2017 to characterize the vegetation and establish the baseline for expanding the Regional Protective Forest Reserve “Serranía El Pinche”, we discovered a new species of the genus Besleria which is described and illustrated here.

The collections of the new species were processed at the herbarium of the Universidad del Cauca (CAUP) and were deposited at the Colombian National Herbarium (COL), the herbarium of the Universidad del Valle (CUVC) and the Botanical Garden of Medellin (JAUM). Specimens of Besleria from COL, CUVC, and JAUM were studied to confirm the identity of the species. The photographs were taken with a Nikon camera model D 5300. For the general botanical terminology we followed Beentje (2010) and Moreno (1984).

Besleria santaclarensis can be readily distinguished from its congeners by the epedunculate inflorescences, usually in the leafless axils near the base of the stem, with up to 8 glabrous orange flowers, and magenta glabrous calyx that covers 2/3 of the corolla. B. santaclarensis is similar to B. membranacea C.V. Morton in their foliage, their flowers with membranous and glabrous calyx, and their slightly gibbous and glabrous corolla tube. B. membranacea is endemic to Peru, particularly to the Amazon and the eastern foothills of the Andes, in the Departments of Loreto and San Martín, mainly in the basin of the Huallaga and Aguaytía rivers, between 260 and 880 m of elevation (Salinas and León 2006). B. santaclarensis differs from B. membranacea by shorter petioles (1.6–4.9 cm vs. (3.2–)6.5–11.6 cm), inflorescences with up to 8 flowers (vs. up to 4), shorter pedicels (8.6–17.1 mm vs. 13.1–20 mm), calyx base truncate to cordate (vs. never cordate), larger calyx lobes (9.0–13.0 × 4.3–10.6 mm vs. 5.8–9.3 × 1.6–4.7 mm) that cover up to 2/3 of the corolla (vs. covering up to 1/2 of the corolla), and corolla tubes shorter (14.4–15.4 mm vs. 14.9–18 mm long) and orange (vs. yellow and white). Additionally, B. santaclarensis is similar to an undescribed species collected in the Province of Zamora-Chinchipe, Ecuador, by Dr. John Clark (Clark et al. 10815). The two species share the inflorescences with several orange flowers with magenta ovate calyx lobes, but differ in that B. santaclarensis has glabrous calyx (vs. pilose) and slightly gibbous and glabrous corolla tube (vs. gibbous and pilose).

With the discovery and description of B. santaclarensis we aim to contribute to the floristic knowledge of this underexplored rainforest in southwestern Colombia, and to provide new information to support the future expansion of the Reserve that will warrant the conservation of this and many other species.

Additional specimens examined (paratypes). Colombia. Cauca: municipio Argelia, corregimiento Santa Clara, vereda El Pinche, zona aledaña a la Reserva Forestal Protectora Regional “Serranía El Pinche”, flanco oriental del Cerro Pinche, camino entre el Plateado y Guapi, en zona cercana a cultivos y pasturas con algunos relictos de bosques secundarios y riparios de la quebrada El Pinche, 2°28.809'N, 77°18.014'W, 1475 m. 11 Feb 2018 (fl, fr). Jhon Alexander Sánchez-Taborda, Fernando Joaquí and Andrés Pérez 2938 (JAUM).

We thank Liliana Patricia Paz-Betancourt and Luis Alfonso Ortega for their dedication and commitment to the conservation of the forests in the department of Cauca (Colombia), and for securing the resources to carry out the field expeditions; the Fund for Partnerships for Critical Ecosystems (CEPF) for financing the study; and Marnix Leonard Becking for managing the funds to make the first explorations to the high parts of the mountain range possible. We also want to thank the Santa Clara Serranía El Pinche Agro-Environmental Association, especially Alveiro Bolaños, community leader, for his dedication to the Reserve; to the field guides Fernando Joaquí and Andrés Perez for their company and teachings during the extensive field days; to the people of Argelia for allowing us to explore part of their territory and for taking the initiative to expand the Reserve; to the Cauca Regional Corporation (CRC) for providing logistical support during the expeditions; to the directors of the herbaria CAUP, COL, CUVC, HUA and JAUM for granting us access to their collections; and to John L. Clark and Ricardo Kriebel for providing helpful reviews and information about collections of species similar to Besleria santaclarensis. Finally, we are grateful to Professor Alvaro Jose Negret (q.e.p.d) for opening the paths that would lead us to explore and conserve these wonderful mountains.