Gastrodia exianlingensis M.Z.Huang, S.R.Lan & Z.J.Liu, 2025

Gastrodia exianlingensis M.Z.Huang, S.R.Lan & Z.J.Liu sp. nov.

(俄fië天※;

Figs 1 View FIGURE 1 , 2 View FIGURE 2 )

Type:— CHINA. Hainan: Dongfang City, Exianling Mountain , elev. 758 m, under the broadleaf forest on limestone, 20 May 2018, Huang 180520001 (holotype: ATCH!).

Gastrodia exianlingensis is similar to G. longitubularis , but differs in longer column foot and lip claw, lip longer than column, and tuber without roots.

Terrestrial, leafless, achlorophyllous herbs. Rhizome tuberous, fusiform, 30–60 mm long, 5–12 mm in diameter, grayish brown, covered with verticillate, triangular-lanceolate scales and finely unicellular hairs. Inflorescence erect, terminal, 7–9- flowered, up to 14 cm long, 2–4 mm in diameter, glabrous, grayish brown, with 5–6 sterile bracts; sterile bracts sheathing, ovate to broadly ovate, 5 mm, apex acute; rachis up to 1.5 cm long. Bracts glabrous, ovate to ovate-oblong, 4.0–6.0 × 2.0– 2.5 mm, apex acute. Pedicel and ovary 8–11 mm long, pedicel slightly curved, ovary 2.5–3.5 mm in diameter, slightly verruculose. Flowers nodding or erect, bell-shaped, widely opening, grayish brown. Perianth tube 18–25 mm long, 5-lobed, slightly verruculose. Sepals 19.0 × 7.1 mm, fused for 4/5 length, and for 4/5 their length with petals, glabrous and grayish brown adaxially; free part of dorsal sepal straight, ovate, 5.7 × 4.4 mm, apex obtuse, slightly concave; free parts of lateral sepals spreading, oblique ovate-triangular, 7.1 × 3.7 mm, entire, apices apiculate, midribs prominently ridged abaxially and slightly elevated adaxially. Free parts of petals ovate-orbicular, 3.4 × 3.4 mm, entire, apex obtuse-rounded, base slightly clawed. Lip adnate to distal part of column foot, free from perianth tube, longer than column, entire, 10 × 5 mm, straight along margin; hypochile yellowish orange, with two yellow, prolate ellipsoid, sessile, nectarless calli; epichile margin undulate and finely contracted in apical portion, disc with 9 longitudinal ridges, the central two ridges much longer and prominent. Column compressed, 8.8 × 1.8 mm, yellowish with dark yellow at base; column foot well developed, about 1.5 mm long; stelidia acute triangular, straight, 1 mm long; rostellum prominent; anther cap abaxially ridged; pollinia ovoid, granular.

Distribution and habitat:— Discovered in the karst rainforest of Exianling Mountain in Hainan Tropical Rainforest National Park. The population was scattered at an elevation of 600– 800 m. Growing in shaded, damp humus among fallen leaves, it was difficult to detect due to its greyish brown stem and flowers.

Phenology:— Flowering May–June.

Etymology:— In reference to the type locality, Exianling Mountain, Hainan Island, China.

Conservation status:— It is an endemic species, known only from Hainan Province, China. Up to now, only about 20 plant individuals of Gastrodia exianlingensis has been found. Due to the habit of mycoheterotrophic plant, accurately assessing the population of this species becomes challenging; therefore, in accordance with IUCN guidelines ( IUCN, 2024), we propose classifying this species as a data deficient (DD).

Taxonomic notes:— Morphologically, Gastrodia exianlingensis is most similar to G. longitubularis and shares a bell-shaped perianth tube, a lip with several longitudinal ridges. However, G. exianlingensis is easily distinguished from G. longitubularis due to its longer column foot and lip claw, lip longer than column and tuber without roots ( Table 1 View TABLE 1 ).