Pleurothallis mark-wilsonii J.S.Moreno, Gal-Tar & Sierra-Ariza, sp. nov.
Creators: name: Moreno, Juan Sebastián
name: Sierra-Ariza, Mario Alexei
name: Hoyos, David
name: Galindo-Tarazona, Robinson
Publisher: name: Zenodo
Year: 2022
Subjects: Biodiversity
Taxonomy
Plantae
Tracheophyta
Liliopsida
Asparagales
Orchidaceae
Pleurothallis
Pleurothallis mark-Wilsonii

description: Pleurothallis mark -wilsonii J.S.Moreno, Gal-Tar & Sierra-Ariza, sp. nov. (Figures 1–2).   
 Type: — COLOMBIA. Valle del Cauca: Municipio de Dagua, Corregimiento de San José del Salado, 1750 m, August 2020, R. Galindo-T & D.L. Mora 3927 (holotype: CUVC!).   
 Pleurothallis mark-wilsonii is most similar to P. amphigya Luer & Escobar (1981: 128) but could be distinguished its petals oblong-lanceolate, revolute and strongly acuminate (vs. elliptical-ovate or subsigmoid, oblique and slightly acuminate) and the lip ovate-lanceolate, with two diverging keels, elongated, located at the base to near the middle of the lip (vs. triangular trilobed, the disc with a developed glenion at the base).   
 Description:— Plant epiphytic, caespitose, medium-sized herb to 17 cm tall. Roots slender, ca. 1.5 mm in diameter. Ramicauls terete, suberect, slender, 3–12 cm long, 1.2–2.2 mm in diameter, pale green, provided with tubular sheaths, short and truncated up to 2.5 cm long at the base, the bracts brown, papyraceous. Leaf suberect, coriaceous, rigid, sessile, elliptical-ovate, acute, slightly acuminate, 4–6 × 2–3.5 cm. Inflorescence, a fascicle of single-flowered peduncles, is born from a reclined spathaceous bract, lanceolate, 0.8 mm long, brown, papyraceous and fibrous when mature, eventually dissolving with age. Ovary straight, striate, papillate, 6–15 mm long. Flowers beige with vinaceous colored microdots, on the lip the dots are much larger and more visible. Dorsal sepal ovate-lanceolate, concave at the base, very involute forming a tube, acute, long-attenuate, 30–35 × 8–13 mm, 3 veined. Lateral sepals connate into a narrow ovate-lanceolate synsepal, concave at the base, very involute forming a tail, acute, long-attenuate, 38–40 × 6–9 mm, 4 veined. Petals oblong-lanceolate, downward inclined, revolute, ciliate, vesiculose to the base, strongly acuminate, 17–20 × 2–4 mm, 3 veined. Lip triangular, trilobed, curved at the basal part when viewed laterally, irregular, salient margins, acuminate, 3.2–3.5 × 2.5–2.8 mm, with two diverging keels, elongated, located at the base to near the middle of the lip. Column semiterete, ventrally vesiculose, stigma apical, prominent margins, 2.8 × 1.5 mm. Anther cap broadly ovate, pale yellow, 2-celled, ca. 0.8 mm long. Pollinia two, narrowly oblong, pyriform, 0.9 mm long, attached to an elliptic viscidium. Fruits not seen.   
 Distribution and ecology: —The species is apparently endemic to the Western Andes in Colombia in the department of Valle del Cauca. It has been found growing as an epiphyte on an Andesanthus lepidotus (Humboldt & Bonpland 1808: 38) Guimarāes & Michelangeli (2019: 948) (Melastomataceae) wood fence at 50 cm from the ground along the edge of a pasture in close proximity to a very well-preserved forest.   
 Additional specimens examined (paratype): — COLOMBIA. Valle del Cauca: Municipio de Dagua, Corregimiento de San José del Salado, Altos de San José del Salado, 1860 m, July 2016, J.S.Moreno & A.L. Erazo 493 (CAUP!).   
 Etymology:— Named after Mark Wilson from the Colorado College in USA. A friend and an arduous researcher of the genus Pleurothallis. His contributions have provided valuable information to solve several taxonomic difficulties within the genus (Figure 3)   
 Taxonomic Discussion: — Pleurothallis mark -wilsonii belongs to the P. subsect. Acroniae ser. Amphigyae (Luer 1998). The most morphologically similar species is probably Pleurothallis amphigya with purple flowers (vs. beige and white flowers with vinaceous dots in the lip and petals), the petals elliptical-ovate or subsigmoid, oblique and slightly acuminate (vs. oblong-lanceolate, revolute, downward inclined and strongly acuminate) and a lip triangular trilobed, the disc with a well-developed glenion at the base (vs. curved at the basal part when viewed lateral, irregular, salient margins, acuminate, with two diverging keels, elongated, located at the base to near the middle of the lip). From Ecuador, Pleurothallis thoerleae (Luer 2012: 337) in Shaw (2016: 39) also from the series Amphigyae is similar to the new species but the latter has rose purple sepals and light yellow-orange petals (vs. beige and white sepals and petals with vinaceous dots), petals linear and gradually acuminate into filamentous tail (vs. oblong-lanceolate and downward inclined and strongly acuminate) finally the lip light-yellow thickly 3-lobed, with the apex broadly rounded with an abrupt apiculum at the center of the margin and the disc with a central pair of rounded parallel calli (vs. ovatelanceolate, acuminate, with the apex acuminate with two diverging keels, elongated, located at the base to near the middle).
description: Published as part of Moreno, Juan Sebastián, Sierra-Ariza, Mario Alexei, Hoyos, David & Galindo-Tarazona, Robinson, 2022, Pleurothallis mark-wilsonii a new species from the subsection Acroniae series Amphigyae from the Western Andes of Colombia, pp. 283-288 in Phytotaxa 568 (3) on page 285, DOI: 10.11646/phytotaxa.568.3.5, http://zenodo.org/record/7529848