Gastrodia punctata Aver., Rheedea

Gastrodia punctata Aver., Rheedea View in CoL 16: 7. 2006. Type: VIETNAM, Lam Dong Province, Lac Duong District, Da Chais Municipality, territory of Bi Doup - Nui Ba National Park, around point 12°06’44” N 108°39’27” E, at 1800–2000 m. on Wester   GoogleMaps slope of Bi Doup Mt.   GoogleMaps , 15.10.2005,

Averyanov, P.K. Loc, J. Regalado, T.T.T. Trang, T.V. Thao, NV. Duy, N.T. Vinh, HLF 5237a (holo HN; iso LE). Figs. 1 View Fig & 2 View Fig

Terrestrial mycoheterotrophic achlorophyllous herbs, with scaly leaves. Roots few, filiform, arising from neck at the top of rhizome, up to 150 mm long, c. 1 mm in diameter, branched. Rhizome horizontal, fleshy, tuberous, irregularly cylindrical to fusiform, gradually narrowed to apex, 25–40 mm long, 5–7 mm in diameter, grayish brown, hairy. Flowering shoot erect, to 250 mm tall, 2–3 mm in diameter at base, unbranched, pale brown at base, dark brown to grayish brown above, with 2–3 membranous sheaths at base and 2–3 scales above. Inforescence racemose, 80–120 mm long, 5–8-fowered; rachis glabrous. Floral bracts ovatetriangular, 1.5–2.0 mm long, 2–2.5 mm wide, glabrous, persistent, dark brown. Flowers pointing slightly downwards, widely opening, bell-shaped, 10–12 mm long, 5–6 mm in diameter, resupinate, brown to grayish brown without silvery white spots. Sepals connate, forming a tube at base, free at apex; dorsal sepal fused with the lateral once about 3/4 their length; lateral sepals fused for 2/3–3/4 their length; free portion of dorsal sepal broadly ovate, 3–4 mm long, 4–5 mm wide, margin slightly undulate, apex obtuse or round; free portions of lateral sepals spreading, ovatetriangular, 4–5 mm long, 4.5–5.5 mm wide, margin slightly undulate, apex acute. Petals attached on the sinus between dorsal and lateral sepals, ovate, 1.8–2 mm long, 1–1.2 mm wide, apex obtuse, base contracted. Labellum free, white with pale orange at base, narrowly ovate, 4.5–5.5 mm long, 3–3.5 mm wide; apex obtuse or truncate, apical margin slightly undulate; base with 2 spherical calli, callus c. 1 mm diameter; disc thickened with distinctly 2-ridged at basal part and two similar keels toward the apex. Column straight, 5–5.5 mm long, white at the upper half and pale brown to grayish brown below; with a pair of triangular stelidia at apex; base with short foot; lateral winged towards apex; rostellum well developed; stigma located near base; anther cap suborbicular, c. 1 mm diameter; pollinia 2, soft and mealy, without caudicles. Pedicel with ovary slightly bent upwards or downwards, 4–5.5 mm long, 2–2.5 mm in diameter, glabrous, dark brown. Capsules not seen.

Flowering & fruiting: Flowers in August; fruits not observed.

Habitat: In Thailand, Gastrodia punctata was found Growing on leaf litter on the forest floor in the lower montane forest at an elevation of c. 2120 m.

Distribution: Gastrodia punctata was previously known from Vietnam ( Lam Dong) and China ( Hainan Island) ( Chen et al., 2023) and now in Thailand. The species may have been overlooked during previous botanical explorations due to its specific habitat and flowering in the rainy season. In Thailand, it is presently known only from Chiang Mai province, but it may have a wider distribution range and could potentially occur in other areas of northern Thailand.

Specimen examined: THAILAND, Chiang Mai, Fang, Doi Pha Hom Pok National Park , N 20°03’13.47”, E 099°08’35.88”, 2120 m 19.08.2022, Sevanakun, Suwanmala & Chantanaorrapint 669 ( PSU, spirit) GoogleMaps .

Conservation status: Gastrodia punctata was first described as a very rare species, known only from one locality in Vietnam ( Averyanov, 2011). Later, Lu et al. (2017) reported this orchid from Hainan Island, and its conservation status was assessed as Critically Endangered (C2ai). This species is now known from three different sites, one in Bi Doup - Nui Ba National Park ( Vietnam), Hainan Bawangling National Nature Reserve ( Hainan Island, China) and Doi Pha Hom Pok National Park ( Thailand). The total number of known mature individuals for this species is fewer than 100. The Area of Occupancy (AOO) is estimated as 12 km 2. Therefore, this species can now be considered as Endangered [EN B2ab (ii,v)] following the guidelines for the IUCN Red List Categories and Criteria ( IUCN, 2024). However, further studies on population size, distribution and population trends and threats are encouraged and it should be reassessed if more information becomes available.

Notes: The collection of G. punctata from Thailand exhibited few minor variations from the type description and the specimens from Hainan Island, such as gray-brown to brown flowers without silvery-white spots ( vs. the presence of 1 silvery-white spots), and labellum being white with pale orange at base ( vs. reddish-orange at apex and base). However, we consider this as natural variation in the species. Gastrodia punctata is morphologically similar to G. huapingensis X.Y. Huang, A.Q. Hu & Yan Liu which is endemic to Guangxi, China ( Huang et al., 2015). These two species share several common features, viz. severalflowered inflorescence, bell-shaped floral tube and labellum with four longitudinal ridges. However, G. huapingensis differs from G. punctata in having dimorphic (straight and incurved) columns. One could argue that G. huapingensis could simply represent an abnormal form of another Gastrodia species, such as G. major Aver. and G. punctata .

There are now eight species of Gastrodia known from Thailand. An updated key to distinguish these species is given below (modified from Suddee, 2014).