Platanthera lachungensis K.Prasad, 2023

Platanthera lachungensis K.Prasad View in CoL , sp. nov. Figs. 3 View Fig & 4 View Fig

Platanthera lachungensis is very similar to P.calceoliformis with its non-resupinate flowers but differs by its non-stoloniferous tuberoids (vs. stoloniferous), yellowish-green or green flowers (vs. deep yellow with dull orange tip), narrowly lanceolate or oblong or oblong-lanceolate sepals, more than 3 mm long (vs. ovate, less than 2 mm long), oblong-lanceolate or lanceolate, not concave lips (vs. broadly ovate when flattened, deeply concave), more than 5 mm long spur with closed mouth and rounded appendage (vs. 0.5 mm long, without appendage).

Type: INDIA , Sikkim, North Sikkim district, Lachung, way to Katao from Lachung , N 27°41’01”, E 88°46’21”, 3275 m, 02.08.2019, K GoogleMaps . Prasad 86542 (holo CAL!; iso CAL!) .

Terrestrial erect herbs, 10–15 cm high. Tubers narrowly fusiform or cylindric-fusiform, 1.5–4 × 0.8–1.2 cm. Stems stout or slender, terete; basal sheaths 2, convolute, oblong-ovate, 1–2 × 0.6– 0.8 cm, acute at apex. Leaves 2 or 3; lower leaf larger than the others, sub-basal, sessile, oblong, 4.5–6 × 1.2–1.5 cm, sheathing at base, entire or sub-entire along margins, acute at apex; upper leaves 1 or 2, oblong-lanceolate or lanceolate, 2–3 × 0.4–0.6 mm, sheathing at base, entire along margins, acute at apex. Inflorescence 8–10 cm long, slender; rachis laxly 5–8-flowered. Pedicel with ovary cylindric, ribbed and beaked, 4–10 mm long, pedicel size increase towards the tip flower. Floral bracts variable (gradually decreasing in size upwards), longer or shorter than flower, linear-lanceolate or ovate-lanceolate, acute or acuminate at apex, 3-veined; lower large floral bracts as long as flowers, 1.2–1.5 × 0.2–0.3 cm; upper small floral bracts shorter than flowers, c. 5 × 2 mm. Flowers non-resupinate, yellowish-green or green, fragrant. Sepals sub-equal, fleshy, margins non-ciliate, apex sub-acute or obtuse, 1-veined; dorsal sepal hooded, narrowly lanceolate or oblong or oblong-lanceolate, 3–7 × 1–1.8 mm; lateral sepals obliquely oblong-lanceolate or lanceolate, 4–7.5 × 1–1.2 mm, longer than the dorsal sepal and petals, spreading, falcate, base with or without one side small triangular appendage. Petals broadly triangular-ovate, 4–6 × 1.2–2 mm, fleshy, margins entire, apex acute, 3-veined. Lip oblong-lanceolate or lanceolate, 4–6 × 0.8–1.4 mm, fleshy, curved near the base, apex obtuse, not dilated basally; spur shorter than or as long as the ovary, stout, incurved, cylindric, 6–10 mm long; mouth of spur closed with rounded appendage. Column erect, 1.6–2 mm long; rostellum small, triangular, obtuse; anther locules situated close to each other, parallel or slightly divergent basally; pollinarium obovoid or pyriform, 0.8–1.1 mm long; caudicle short, c. 0.2 mm long; viscidium flat, narrowly oblong-lanceolate, c. 0.3 mm long; staminodes sub-orbicular; stigma globose, with protruding lateral lobes, median lobe inconspicuous. Capsules ovoid.

Flowering & fruiting: July to September.

Habitat: It grows on open slopes of moss-covered sub-alpine and alpine areas, at an elevation of more than 3000 m.

Etymology: The species is named after the type locality, Lachung in North Sikkim.

Distribution: Hitherto known only from the type locality.

Conservation status: Platanthera lachungensis has about 50 individuals in the type locality area. All the individuals were observed in an area around 1 km 2. The type locality is a restricted area under the jurisdiction of the Indian army. Further explorations in the adjacent areas are necessary to ascertain its status, hence it is assessed here as ‘Data Deficient’ ( DD) ( IUCN, 2022) .

Notes: Generally, species in this genus have resupinate flowers but present new species ( P. lachungensis ), P. nivea (Nutt.) Luer (America), P. calceoliformis and P. superantha (Asia) have non-resupinate flowers. The new species is closely allied to P. calceoliformis but it is easily distinguishable from the latter by the characters which are discussed in diagnosis. The new species also shows congruence with P. pachycaulon but differs by having 10–15 cm tall plants (vs. 12–45 cm tall), lower larger leaf sub-basal, oblong (vs. usually situated below the middle of the stem or rarely near the middle, ovate to narrowly lanceolate), non-resupinate flowers (vs. resupinate), margins of sepals entire (vs. papillose), mouth of spur with rounded appendage which is closed at the entrance (vs. without any appendage and stigma lobes closed at the entrance).