Pleurothallis sabanillae M. M. Jimenez & Velez-Abarca 2023, sp. nov.
Creators: name: Jiménez, Marco M.
name: Vélez-Abarca, Leisberth
name: Mashendo-Jimbicti, Viviana
name: Garzón-Suárez, Henry X.
name: Monteros, Marco F.
name: Wilson, Mark
Publisher: name: Zenodo
Year: 2023
Subjects: Biodiversity
Taxonomy
Plantae
Tracheophyta
Liliopsida
Asparagales
Orchidaceae
Pleurothallis
Pleurothallis sabanillae

description: 4. Pleurothallis sabanillae M.M.Jiménez & Vélez-Abarca, sp. nov. (Figures 9–10).
Type: — ECUADOR. Zamora Chinchipe: Loja-Zamora road, near El Tambo, 3°56’40.08’’ S, 79°02’45.00’’ W, 2102 m, 4 August 2022, M. Jiménez & L. Vélez-Abarca 1253 (holotype: HUTPL 14636!).
Similar to Pleurothallis lilijae Foldats (1968: 379), from which it differs by its broadly ovate, 7–veined dorsal sepal (vs. broadly elliptic, 5–veined), ovate, 3-veined petals (vs. triangular ovate, 1-veined), the obtuse, convex lip (vs. triangular, concave) with a deep, broad glenion and an apical sulcus (vs. shallowly concave, small and no sulcus).
Description:— Plant epiphytic, up to 36 cm tall, descendent to pendent; roots slender, flexuous, 0.6–1.3 mm in diameter. Ramicauls slender, suberect, terete, 11.1–19.4 cm long and 0.1 cm in diameter, enclosed by papyraceous, tubular sheaths, upper sheath 12.9–18.9 mm long, basal sheath 6.2–7.7 mm long. Leaves deflexed, coriaceous, microscopically papillate, lanceolate to narrowly ovate, channeled in the middle, 2.4–3.7 × 12.0– 14.5 cm, acuminate at the apex, the base sessile, deeply cordate with the lobes unequal up to 1.6 cm long. Inflorescence a fascicle of successive flowers produced from a suberect, scabrous spathaceous bract, 1.1–1.3 mm long; floral bract infundibuliform, 4.4– 4.6 mm long; pedicel subflexuous, 2.4–3.5 mm long. Flowers resupinate or not, glossy, dorsal sepal purple with yellow borders to pale yellow suffused with purple at the base and veins, broadly ovate, subacute to obtuse, strongly deflexed at the apex, 9.8–11.5 × 8.9–9.4 mm, 7-veined, subverrucose-papillose, minutely pubescent, convex below the middle; lateral sepals connate into a 6-veined, elliptical-oblong, subverrucose-papillose, strongly revolute margins, purple with yellow borders synsepal, 6.1–6.5 × 2.9–4.6 mm. Petals purple with yellow borders, ovate above the third quarter, oblique, narrowed below the middle, shortly attenuate, strongly deflexed near the apex, acute, 8.1–10.1 × 4.1–5.0 mm, 3-veined, pubescent-verruculose, margins ciliate-denticulate, revolute. Lip dark purple with paler or whitish border, broadly ovate, obtuse, diffusely glandulous-verrucose, concave, 2.7–2.9 × 3.3–3.5, 3-veined, margins thickened, involute apically; the base subtruncate, hinged to the column foot, with very short obtuse angles and a large, deep, obovoid glenion, occupying the middle third of the lip, concave and deeply sulcate towards the apex of the lip. Column dark purple, transversely subrectangular, dorsally complanate, 2.8 × 3.0– 3.2 mm, papillose, glandulous on the edges, stout, 3-ribbed dorsally, stigma transversely bilobed with minutely ciliate margins, rostellar flap 0.4 mm long. Anther narrowly triangular-obovate, white to pale yellow, papillose, 1.1 mm long, bilobed at the base. Pollinarium with 2 obovoid, yellow pollinia, 0.9 mm long, brought together by a drop-like viscidium. Capsules 1.6 × 0.3 cm. Ovary subverrucose-glandulous, straight, 2.6–3.0 × 1.0 mm.
Distribution and ecology: —Up to now Pleurothallis sabanillae is only known from the steep hillsides near the village of Sabanilla in the Zamora Chinchipe province of Ecuador (Figure 3). The species is found growing as an epiphyte on understory lianas and tree trunks, together with other orchid species such as Elleanthus vernicosus Garay (1978: 105), Octomeria colombiana Schlechter (1920: 121), O. hirtzii Luer (2002: 29), Pleurothallis adonis Luer (1976: 40) and P. omoglossa Luer (1976: 152). The upper montane forests of this region are dominated by Purdiaea nutans Planchon (1846: 251), Myrica pubescens Humboldt & Bonpland ex Willdenow (1806: 746), Myrsine andina (Mez 1902: 378) Pipoly (1992: 7) and pioneer species such as Andesanthus lepidotus and Graffenrieda harlingii Wurdack (1976: 7) (Bussman 2005).
Etymology: —Named after Sabanilla, known also as El Tambo, an eminent farming village in the Zamora Chinchipe Province of Ecuador close to the type locality.
Taxonomic discussion: — Pleurothallis sabanillae belongs to the Pleurothallis cardiostola-lilijae complex, a group within the subsection Macrophyllae-Fasciculatae according to Luer (2005) and Wilson et al. (2022). The new species is most similar to Pleurothallis lilijae, but is distinguished by the shorter plants (up to 36 cm vs. 45 cm tall) and flowers (1.1 × 1.6 vs. 1.6 × 2.2 cm), the purple flowers (vs. pale yellowish brown), the strongly deflexed dorsal sepal (vs. erect), strongly recurved petals (vs. slightly deflexed), the broadly ovate lip (vs. ovate-triangular) and the purple column (vs. purple and white).
Conservation status: —To date this species is known from one locality with a few dozens of individuals we recommend to consider it as a restricted endemic. Pleurothallis sabanillae is present near forests threatened by human activities (frequent forest fires, works close to high voltage electrical lines, livestock breeding and deforestation). Fortunately, this species is expected to be found within the Podocarpus National Park, where its conservation would be assured.
description: Published as part of Jiménez, Marco M., Vélez-Abarca, Leisberth, Mashendo-Jimbicti, Viviana, Garzón-Suárez, Henry X., Monteros, Marco F. & Wilson, Mark, 2023, Five new species of Pleurothallis (Orchidaceae: Pleurothallidinae) in subsection Macrophyllae-Fasciculatae from Southeastern Ecuador, pp. 161-181 in Phytotaxa 607 (3) on pages 171-173, DOI: 10.11646/phytotaxa.607.3.1, http://zenodo.org/record/8243217