Lepanthes pterygion is a small, epiphytic, caespitose orchid with comparatively coarse roots. The ramicauls are erect and slender, 1–4 cm long, enclosed by 6–7 minute, microscopically ciliate lepanthiform sheaths with dilated ostia. The single leaf is suffused with purple, erect, coriaceous, ovate, acute to acuminate, 1–2 cm long and 0.6–1 cm wide, with the rounded base contracted into a 0.5 mm-long petiole.

The inflorescence is a dense, secund, successively flowered raceme up to 8 mm long, borne by a filiform peduncle 4–20 mm long; floral bracts 0.5 mm long; pedicels 2 mm long; ovary 1.5 mm long. The sepals are translucent magenta with darker veins, glabrous and with smooth margins. The dorsal sepal is triangular-ovate, acute, 5 mm long and 2.5 mm wide, 3-veined, fused to the lateral sepals for 0.5 mm. The lateral sepals are ovate, oblique, subacute and diverging, fused 1.5 mm, each 4.5 mm long and 4 mm wide together, 2-veined.

The petals are dark red-purple, microscopically pubescent, transversely elliptic and very small — only 0.5 mm long and 2.75 mm wide, with subequal narrowly triangular, acute lobes. The lip — the namesake feature — is 2 mm wide, suffused with rose, microscopically pubescent and transversely elliptic, three-lobed, with a shallow concavity near the middle. The anterior lobe is ligulate, obtuse, 0.5 mm long, while the lateral lobes are triangular, narrowly obtuse, acute and surround the column below the middle — these are the "tiny wings" from which the species takes its name. The base of the lip is fused to the base of the column. The column is arcuate (decurved), 2 mm long, with a bidentate apex, subapical anther, and ventral stigma.

The morphological characters described here follow Luer & Escobar (1984), as reproduced in Luer & Thoerle (2012) in Icones Pleurothallidinarum XXXII.

The published literature describes Lepanthes pterygion as an epiphyte of cloud and montane forest in the Cordillera Central of Antioquia. The protologue (Luer & Escobar, 1984) cites paratypes at elevations between 1,730 and 2,000 m at Yarumal (Alto de Ventanas) and Cocorná, with additional records along the road to Briceño at 1,850 m. Luer's discussion notes that L. pterygion "has been collected on numerous occasions in Colombia," indicating that despite being a narrow Antioquian endemic, the species has multiple known localities across northern and eastern Antioquia.

In La Honda, L. pterygion has been observed between approximately 2,200 and 2,400 m as an epiphyte on twigs and branches of mature montane forest. The local distribution pattern is distinctive: rather than scattered singletons, the species occurs in clustered colonies of plants — and only in the most conserved forest patches at the site. This "best-forest" association is a meaningful field signal: it implies that L. pterygion depends on the structural integrity, microclimate stability, and substrate continuity of mature, undisturbed forest, and that the species is among the first to be lost where forest quality declines. The pattern at La Honda corroborates the criteria underpinning the species's 2025 IUCN Endangered assessment.

Lepanthes pterygion is endemic to Colombia and known from northern and eastern Antioquia in the Cordillera Central (POWO, 2026; Luer & Escobar, 1984; Luer & Thoerle, 2012; Idárraga-Piedrahita et al., 2011).

The protologue (Luer & Escobar, 1984) cites the holotype from Yarumal, Alto de Ventanas, at 2,000 m — collected by R. Escobar and E. Valencia (no. 2618) on 20 May 1983, deposited at SEL with C. Luer's illustration 9099. Paratypes span a notable elevational and geographic range: Quebrada El Oro at 1,730 m (Escobar & Valencia 2652), the type locality of Cocorná, epiphytic in cloud forest near Río Cocorná at 1,900–2,000 m (Luer, Luer, Escobar & Valencia 10086, MO), and a further collection from Yarumal "epiphytic in forest remnant along the road to Briceño" at 1,850 m (Luer, Luer, Dalström & Teague 14189–14201, 1989).

The Cocorná record places L. pterygion alongside L. cerambyx and L. viahoensis among the species in this book documented from the Cocorná drainage — a recurring eastern-Antioquian locality thread that connects multiple sheets in the project. The La Honda record at 2,200–2,400 m sits above the elevational ceiling reported in the protologue (2,000 m), extending the documented elevational range of the species; the substrate and microhabitat preferences observed at La Honda are nonetheless consistent with the species's documented niche.

Flowering has been observed at La Honda. The available data are not yet sufficient to characterise local phenology with precision; systematic observation across a full annual cycle would be required to identify flowering peaks or quiescent periods. The dense, secund, successively flowered raceme architecture noted in the protologue means that fertile plants commonly bear several flowers at different stages of development simultaneously, with one flower at peak anthesis and others in bud or post-anthesis. The two-flower stage visible in the photographs accompanying this sheet — one fully open, the other in late bud or early opening — illustrates this raceme architecture clearly.

Lepanthes pterygion is, in your interviewer's own words at the time of fieldwork, "very recognisable for its shape and reduced petals." The diagnostic combination is unmistakable once the search image is acquired:

Vegetatively, look for small erect plants with ramicauls 1–4 cm long bearing a single purple-suffused, ovate, erect leaf 1–2 cm long. The purple suffusion of the leaf is itself a useful field signal — most other Lepanthes at La Honda have entirely green foliage.

Florally, the diagnostic features are: (i) translucent magenta sepals with darker veins, with the dorsal triangular-ovate and acute, the laterals fused into a broadly ovate-oblique synsepal, and the upper sepal often arching forward in a winglike sweep over the rest of the flower; (ii) strikingly reduced dark red-purple petals — only 0.5 mm long, transversely elliptic, almost obscured by the column complex — that give the flower its distinctive minimalist proportions; (iii) the decurved (arcuate) column flanked at its base by a pair of tiny, winglike lateral lobes from the lip — the namesake "pterygion" feature, a floral architecture that Luer in his discussion described as "unusual" within the genus.

Luer's protologue diagnosis links L. pterygion uniquely to L. yubarta E. Calderón (a species not present at La Honda or in this book), which shares the decurved column and lip-wing pair. The two species are distinguished by sepal proportions, petal lobe shape, and the lip blade and appendix dimensions — but the decurved column with lip-wings is unique within the project's Lepanthes set to L. pterygion, making this character alone sufficient for confident field identification.

Lepanthes pterygion is classified as Endangered (EN) on the IUCN Red List, formally assessed in 2025 by Moreno, Vieira-Uribe and Ávila-R. The same Endangered classification applies at the national regulatory level: L. pterygion is listed in Resolución 0126 de 2024 of the Colombian Ministry of Environment as a threatened species under Colombian environmental law.

Lepanthes pterygion is the first species in this book to carry an Endangered classification at both global and national scales. "Endangered" is the IUCN's second-highest threat category for evaluated species, applied to taxa considered to be facing a very high risk of extinction in the wild based on rapid range or population decline, severely fragmented populations, or restricted distribution combined with continuing decline. For L. pterygion, the assessment criteria reflect the species's narrow Antioquian range, its dependence on intact mature forest, and the sustained pressure on that forest matrix from agricultural expansion and fragmentation across northern and eastern Antioquia.

The local pattern at La Honda directly corroborates the assessment's habitat-quality framing. L. pterygion occurs at La Honda only in the most conserved forest patches, in clustered colonies that depend on the structural and microclimatic continuity of mature forest. Where forest quality declines, this species is among the first to disappear. Locally — at La Honda and elsewhere within the species's range — persistence depends on the long-term protection of mature montane forest at approximately 1,700–2,400 m, and on preventing the further fragmentation of the forest matrix that links the species's known localities.

For these reasons — and to maintain consistency with the locality-redaction practice applied to the other Lepanthes sheets in this book — the specific location within La Honda where L. pterygion has been documented is not published, and precise elevation data beyond the approximate 2,200–2,400 m tier are redacted from this sheet. Requests for further locality detail from researchers or conservation practitioners with a legitimate scientific or institutional purpose may be directed to [email protected].