Pleurothallis machupicchuensis Damian-Parizaca, Monteros & Coayla 2025, sp. nov.
Creators: name: Damián-Parizaca, Alexander
name: Monteros, Marco Federico
name: Coayla Rimachi, Daxs
name: Walston, Joseph
name: Mitidieri-Rivera, Nicole
Publisher: name: Zenodo
Year: 2025
Subjects: Biodiversity
Taxonomy
Plantae
Tracheophyta
Liliopsida
Asparagales
Orchidaceae
Pleurothallis
Pleurothallis machupicchuensis

description: Pleurothallis machupicchuensis Damián-Parizaca, Monteros & Coayla sp. nov.
Figs 1, 2, 3 A, 4
Type.
Perú • Cusco, Prov. Urubamba, Aguas Calientes, property of the Machupicchu Pueblo Hotel, 2000 m, 30 November 2023, Daxs Coayla 001 (holotype: CUZ).
Diagnosis.
Pleurothallis machupicchuensis is most similar to Pleurothallis scurrula Luer but differs by the obtuse dorsal sepal (vs. acute), the acute synsepal apex (vs. obtuse to rounded), the falcate petals (vs. oblong-ovate), the ovate lip (vs. oblong), and the reniform bilobed glenion (vs. oblong non bilobed).
Description.
Plant epiphytic, caespitose, erect 15 cm tall. Roots slender, flexuose, up to 0.1 cm in diameter. Ramicauls erect, 10–15 cm long, 0.1 cm in diameter, slightly curved at the apex forming an angle of about 100 ° in the abscission layer, enclosed by two basal papyraceous, sulcate, brownish, tubular sheaths, 4.0– 6.5 cm long. Leaf borne at the apex of the ramicaul, suberect to nearly horizontal, pale green, slightly coriaceous, deflexed toward the base, somewhat concave, lanceolate, with a short concavity at the base of the spathe, margins entire, acuminate, 5.0–7.7 × 2.0–3.0 cm, base sessile, cordate, lobes equal. Inflorescence a single-flowered coflorescence borne erect from a depressed, conduplicate, oblong, obtuse, sub-erect spathe at the base of the leaf, 0.8–1.0 cm long, striate, brownish, dry-papyraceous when mature, concealing peduncle, branch system, pseudopeduncle and pedicel; pseudopeduncle terete, up to 0.4 cm long; pedicel yellowish, flexuose, terete, 1.0– 1.5 cm long; ovary terete, blackish to brownish, furrowed, 0.5–0.7 cm long. Flowers non-resupinate, spreading, yellowish to citrine colored, column yellowish to whitish, anther cap and stigma yellowish, lip overall yellowish sometimes with reddish margins. Dorsal sepal erect slightly convex, ovate, glabrous, obtuse, 3 - veined, 1.0 × 0.5 cm. Lateral sepals connate into a broadly ovate synsepal, centrally concave-channeled, obtuse, glabrous, margins entire, 0.8 × 0.6–0.7 cm, 4 - veined. Petals strongly reflexed, falcate, 1 - veined, conspicuously papillate on the margins, 0.6–0.7 × 0.1 cm. Labellum overall ovate, obtuse at the apex, slightly ascending, strongly verrucose-bullate towards the margins, papillae grouped into clumps of around 5–6 papillae, clumps join together to form nearly horizontal linear groups that follow down to the base, centrally sulcate, base acutely deflexed upon itself hinged to the column-foot, 0.3 × 0.2 cm; glenion bilobed, hourglass-shaped, ca. 400 µm wide, ca. 150 µm at its shortest, and ca. 250 µm at its longest length, papillae at the glenion boundary smooth and notably larger and taller, width 25 µm and length 35 µm, papillae found outside of the glenion are highly textured, width 25 µm. Column short, stout, complanate, 0.2 cm long, minutely papilose, rostellar flap long, linear, obtuse. Anther apical, incumbent, anther cap cucullate, ovate, 2 - celled, 0.8 × 0.6 mm. Stigma apical, bilobed, reniform. Pollinia two, narrowly pyriform, 0.1 cm long attached to an elliptic viscidium. Fruit unknown.
Phenology.
This species has been observed flowering in two seasons: April and from October to December.
Etymology.
The epithet honors the llaqta Machupicchu, an Inka citadel in Cusco, southern Peru, located within the Urubamba Province, where P. machupicchuensis is locally distributed.
Distribution and habitat.
Pleurothallis machupicchuensis primarily grows on trees of the genus Clusia L. within typical montane forest vegetation. Known populations are located along the Urubamba and Usmubamba Rivers in the provinces of Urubamba and La Convención, respectively, as well as within the Machu Picchu Historic Sanctuary, at elevations ranging from 2000 to 2500 meters (Fig. 2).
Conservation status.
Although the known distribution of Pleurothallis machupicchuensis is within the Machu Picchu Sanctuary, sufficient information is still lacking to assess its preliminary conservation status. Therefore, we recommend classifying this species as Data Deficient (DD) according to the IUCN (2022) criteria.
Taxonomic notes.
Pleurothallis machupicchuensis is readily distinguished by the combination of a large dorsal sepal (relative to the synsepal), non-resupinate flowers, falcate petals, and an ovate lip that is conspicuously sulcate and features a prominent bilobed glenion (Figs 1, 2 A). The species was first photographed in 1998 at the Inkaterra Pueblo Hotel and has since been mistakenly identified as Pleurothallis phyllocardioides Schltr. (Collantes et al. 2007; Ochoa 2023). Luer (2005) recognized P. phyllocardioides as part of a species complex widely distributed from Central America throughout the Andes. This complex is characterized by having short and non-reflexed petals measuring 2–3 mm, and an ovate-oblong lip with an unlobed glenion. These features differ significantly from strongly reflexed petals measuring 6–7 mm, and the ovate lip with a bilobed glenion observed in P. machupicchuensis (Fig. 3 A, B). Furthermore, Andean populations of P. phyllocardioides reported by Luer (2005) are found in submontane forests below 1200 m altitude, whereas P. machupicchuensis has so far been documented exclusively in montane forests above 2000 m. Additionally, P. phyllocardioides appears to be restricted to Central America (M. Wilson, pers. comm.), and Peruvian populations previously described as Pleurothallis graciliscapa C. Schweinf. (= P. phyllocardioides sensu Luer 2005) show minimal divergence from the typical Central American morphotype, rendering their resemblance to P. machupicchuensis less plausible.
The Peruvian Pleurothallis scurrula is the most morphologically similar species to P. machupicchuensis but can be readily distinguished, primarily by its petal shape. In P. scurrula, the petals are oblong-ovate, whereas in P. machupicchuensis, they are conspicuously falcate. The two species are also differentiated by the morphology of the labellum, which is clearly rounded in P. scurrula and obtuse in P. machupicchuensis. Furthermore, P. machupicchuensis possesses a conspicuous bilobed glenion, contrasting with the minute, rounded glenion of P. scurrula. Another morphologically similar species is the Colombian Pleurothallis sannio Luer & R. Escobar, which can be distinguished by its slightly shorter flowers, with sepals measuring 8 mm in length (versus 10 mm in P. machupicchuensis), and its obovate synsepal (versus ovate). Most notably, P. sannio lacks a bilobed glenion and a central furrow on the lip, features that are diagnostic of P. machupicchuensis (Table 1, Fig. 3 C).
Other records.
Perú • Cusco, Prov. Urubamba, Aguas Calientes, Catarata de Mandor, December 20, 2021 [flower] https://www.inaturalist.org/observations/103258849; • ibid. January 5, 2013, [flower] https://www.inaturalist.org/observations/96696628; • Prov. La Convencion, Usmabamba, February 10, 2020 [flower] https://www.inaturalist.org/observations/68871779; • Prov. Urubamba, Machu Picchu Historic Sanctuary, 1998, reported by the Inkaterra Association Research Team, pl. 114 as Pleurothallis phyllocardioides Schlechter (Collantes et al. 2007); • Machupicchu Historical Sanctuary, at 1900–2500 m, March 24, 2012 [flower] https://bit.ly/3WtKfEB; • Cusco, Aguas Calientes, 26 April 2010 [flower] https://bit.ly/4ao1Vak.
description: Published as part of Damián-Parizaca, Alexander, Monteros, Marco Federico, Coayla Rimachi, Daxs, Walston, Joseph & Mitidieri-Rivera, Nicole, 2025, A new species of Pleurothallis (Pleurothallidinae, Orchidaceae) from the historic sanctuary of Machupicchu, Perú, pp. 29-40 in PhytoKeys 254 on pages 29-40, DOI: 10.3897/phytokeys.254.142116