Platystele riograndense Reina-Rodr. & Karremans, 2018

Reina-Rodríguez, Guillermo A. & Karremans, Adam P., 2018, A new Platystele (Orchidaceae, Pleurothallidinae) from the western mountains of Colombia, Phytotaxa 375 (3), pp. 235-242 : 236-240

Platystele riograndense Reina-Rodr. & Karremans sp. nov. ( Figs. 1–3 )

Diagnosis:— Platystele riograndense Reina-Rodr. & Karremans is similar to P. filamentosa Luer but the new species has broader leaves (5 vs 3–4 mm), a dense (versus loose) inflorescence that slightly exceeds the leaf (vs. more than twice the length of the leaf), denser and shorter inflorescences (17 vs. 60 mm long), narrowly oblong (vs. ovate) sepals, ligulate (vs. filamentose) petals, and a sigmoid (vs. convex), obtuse (vs. acute) lip.

Type:— COLOMBIA. Valle del Cauca: Municipio de Restrepo, Vereda Román, Cuenca alta del río Dagua, Distrito de Conservación de Suelos Cañón de río Grande, Reserva Natural de la Sociedad Civil Las 3R’s, Bosque de Niebla. 1675 m, 30 de marzo 2013, Epífita miniatura, creciendo sobre Spirotheca rhodostyla Cuatrec., G. Reina-Rodríguez, T. Otero, N. Flanagan & F. López 1603 (holotype CUVC –Spirit).

Description:— Epiphytic plant, caespitose, erect, up to 1.7 cm tall, including the inflorescence. Roots basal, swollen and sinuous up to 6 mm long. Ramicauls erect, short, enclosed by sheaths. Sheaths tubular, compressed, membranous, brownish with stretch marks up to 3.0– 3.5 mm. Leaf blade 5 mm wide, rounded, 5-veined, spatulated, conduplicate, basally cuneate, which forms an angle of 135 degrees and terminating in a short apiculus, 0.5 mm. Peduncle 13–17 mm long, racemose, filiform and terete, shortly surpassing the leaf. Pedicels 2.5–3.0 mm, congested, distichous, teretes forming an angle of 15 degrees with the peduncle, with one flower produced at time by pedicel. Ovary 0.6 mm long with ribs. Flower 1.8 mm tall x 1.5 mm wide, with the sepals, petals and column yellowish translucid, the lip red translucid. Dorsal sepal 0.8–0.9 × 0.4–0.5 mm, narrowly oblongo-acuminate, margin smooth. Lateral sepals 1.0–1.2 × 0.5–0.6 mm narrowly oblongo-acuminate, margin smooth 1-veined Petals 1.2 × 0.3 mm, filiform, and curve forward, smooth margin, acute. Lip 1.1–1.3 × 0.5 mm. equal length of the lateral sepals, narrowly-ovate, convex, acute-rounded with the tip curve forward, margin smooth. Column short 0.4–0.5 mm long, distally apiculate, with lobules cucullate and margin fimbriate. Anther apical cucullate, pollinia two, laterally flattened. Fruits not seen.

Eponymy:— The name honors the Rio Grande canyon, in the upper part of the Dagua river basin, between the municipalities of La Cumbre and Restrepo in Valle del Cauca, Colombia ( Fig. 4). There the tropical dry forest and moist dense forest converge, and a public protected area of 10700 hectares has been recently created. The dense moist forest where the new species was discovered ( Fig. 5 ) has been preserved by the Reina-Ramos family for more than a century.

Phenology:— The plant was registered to flower in March in situ, coinciding with the beginning of the rainy season.

Ecology and distribution:— Platystele riograndense is currently known only from the type specimen. It was found growing upper part of the Dagua river basin, in the Valle del Cauca department of Colombia, growing at an elevation of about 1,675 m. The area has been classified as lower montane humid forest ( Holdridge 1987), and reports precipitations between 1,400 and 1,600 mm. The average annual temperature is 18°C. The protected area –DCS– Cañón de río Grande of 10,700 hectares forms an altitudinal complex (geocomplex) in sense ( Vigo 1998) from subxerophytic schrubs (710 m) to cloud dense forest (1,780 m). Platystele riograndense was found towards the upper part (at 1,675 m), in the summit zone, with sub-Andean flora whereas P. filamentosa Luer grows in more extensive and wet areas of primary Andean forest. (see table 1). The P. riograndense grows on Spirotheca rhodostyla Cuatrecasas (1945: 274–299) however, the P. filamentosa phorophyte is unknown. The P. riograndense vs. P. longicaudata flora canopy above 25 m high is dominated by Poulsenia armata ( Miquel 1854: 197–200) Standley (1933: 4) , Cecropia telealba Cuatrecasas (1945: 293) , vs. Elaeagia utilis ( Goudot 1844: 260) Weddell (1849: 94) and Hieronyma oblonga ( Tulasne 1851: 248) Müller (1865: 66) . Subdosel species (10–20 m) Cosmibuena grandiflora ( Ruiz & Pavón 1799: 198) Rusby (1907: 368) and Heliocarpus americanus Linnaeus (1753: 448) vs. Faramea calyptrata Taylor (1999: 280) and Carapa guianensis Aublet (1775a: 32) . Shrub vegetation (<10 m). Hedyosmum bonplandianum Kunth (1825: 165) and Palicourea thyrsiflora ( Ruiz & Pavón 1799: 198) Candolle (1830: 528) vs. Faramea coffeoides Taylor (1999: 284) and Palicourea gibbosa Dwyer (1980: 304) The palms comunity: Prestoea decurrens (H.Wendland ex Burret 1930: 123–270) Moore (1963: 286) and Chamaedorea pinnatifrons ( Jacquin 1797: 1–68) Oersted (1858: 1–54) vs. Prestoea acuminata ( Willdenow, 1804: 35) Moore (1963: 286) and Aiphanes erinacea ( Karsten 1857: 391) Wendland (1878: 230) . Also, there is a community of epiphytes dominated by Tillandsia fendleri Grisebach (1864: 17) , Tillandsia adpressa André (1888a: 6) , Monstera adansonii Schott (1830: 1028) , Anthurium scandens ( Aublet 1775b: 828–833) Engler (1878: 78) and Guzmania scherzeriana Mez (1896: 949) vs. Philodendron verrucosum Mathieu ex Schott (1856: 85) , Anthurium longicaudatum Engler (1898: 388) and Guzmania sprucei (André 1888:b 5) Smith (1934: 75) ( Fondo Acción et al. 2013; Velázquez et al. 2006).

This is the second new species discovered in the area in the last four years after Encyclia parkeri Reina-Rodriguez & Leopardi in Leopardi-Verdi et al. (2014: 164) from the middle part of basin.

Conservation status:— An assessment of its conservation status cannot be made at this time and has to be classified as data deficient (DD) because further information and research is required in the future to recognize their threat status ( UICN 2012).

Discussion:— Important morphological differences were observed between Platystele riograndense and P. filamentosa , a dense (versus scattered) inflorescences (17 vs. 60 mm long) and sigmoid (versus convex) lip, narrowly oblong (vs. ovate) sepals, ligulate (vs. filamentose), and a sigmoid (vs. convex), obtuse (vs. acute) lip. In terms of biogeography, phenology, plants communities, habitat and abiotic conditions are presented in Table 1.

Adittionally, Platystele riograndense differ from P. filamentosa in terms of: 1) Phenology flowering: March vs. July 2) Geography: Valle del Cauca (Center) vs. Nariño (South) 3) Life zone: Pre-montane wet forest vs. Montane rainy forest 4) Elevation: 1675 vs. 1820 m altitude 5) Mean annual rainfall: 1400–1600 vs. 3800–4000 6) Humidity 82% vs. 91% 7) Mean temperature 20.2 °C vs. 19.2 °C and 8) Ecological niche: The plants communities sampled in these locations are very different ( Fondo Acción 2013, Velazquez et al. 2006).

Areas with similar conditions have been detected in the “Farallones de Cali National Park” and “Munchique National Park” booth on the Pacific slope, but with a huge flora gaps. These national parks have ecological conditions for the presence of both species.

Figures

FIGURE 1. Platystele riograndense Reina-Rodr. & Karremans.A. Habit. B. Inflorescence. C. Lateral, frontal and 3/4 view of the flower. Photographs by F. López-Machado of the plant that served as type.

FIGURE 2. Platystele riograndense Reina-Rodr. & Karremans. A. Habit. B. Lateral, frontal and 3/4 view of the flower. Illustration by Joan Ramírez based on photographs by F. López-Machado and Maria C. Benavides-Guzman of the plant that served as type.

FIGURE 3. Platystele riograndense Reina-Rodr. & Karremans. A. Inflorescence. B. Leaf apex. Photographs by G. Reina-Rodríguez of the plant that served as type.

FIGURE 5. Landscape and vegetation of the area where the type specimen of P. riograndense was collected. Photographs G. Reina- Rodríguez.