Gastrochilus jiuzhaigouensis Jun Y. Zhang, D. L. Zhu & Y. Zhang, 2025

Zhu, Da-Lin, Zhang, Jun-Yi, Zhang, Yue, Liao, Min, He, Hai, Chen, Ke & Xu, Bo, 2025, Gastrochilus jiuzhaigouensis (Orchidaceae, Epidendroideae), a new epiphytic orchid from Jiuzhaigou World Heritage Site, China, PhytoKeys 265, pp. 25-38 : 25-38

Gastrochilus jiuzhaigouensis Jun Y. Zhang, D. L. Zhu & Y. Zhang sp. nov.

Figs 2 D, E , 3

Type.

China • Sichuan: Jiuzhaigou, Wuhuahai (the Colorful Lake) , lake bank trees at border of subalpine mixed coniferous forest, on dieback tree branches, elev. ca. 2,478 m, in flower, 23 April 2024, Jun-Yi Zhang & Da-Lin Zhu ZJY 195 ( Holotype CDBI!; Isotype CDBI!) .

Diagnosis.

It is most similar to G. bernhardtianus , but it can be distinguished by its shorter stem (0.5–1.2 vs. ca. 5.0 cm), obliquely linear-lanceolate leaves (vs. oblong-lanceolate leaves), reniform and revolute epichile (vs. transversely oblong and spread) without ornamentation (vs. two conic calli near its base), and absence of middle ridge (vs. distinctly ridged) at the middle of central callus on the epichile.

Description.

Miniature branch epiphyte, pendent, 2.0–4.0 cm tall. Roots vermiform, 3.0–5.0 cm long, ca. 1.2 mm in diameter. Stem unbranched, 0.5–1.2 cm long, ca. 1.2 mm in diameter. Leaves thickly leathery (with fleshy mesophyll), tinged with purplish-red spots, closely arranged, distichous, alternate; blade obliquely linear-lanceolate, 1.2–2.4 × 0.3–0.6 cm, base slightly asymmetry, apex acute and ended with one lobule, lobes setaceous. Inflorescence a 1 - or 2 - flowered on a short rachis; peduncle curved upward and thickened, 3.0–6.0 mm long, proximally covered with one sheath; floral bracts ovate-lanceolate, 0.6–1.0 mm long, apex acute; pedicel and ovary connate, 0.8–1.1 cm long. Flowers spreading, ca. 0.8 × 1.2 cm; sepals and petals yellow-green on both sides; dorsal sepals elliptic, 4.8–6.0 × 3.6–4.2 mm, apex obtuse; lateral sepals oblong, 5.0–6.8 × 3.0–4.0 mm, apex obtuse; petals obovate, 4.0–5.8 × 3.0–4.0 mm, apex obtuse, base narrowed; lip with a reniform epichile, revolute, purplish-red, 8.0–10.0 × 4.2–5.5 mm, margin entire, smooth and glabrous above, centra thickened purple-yellow without ornamentation; hypochile sub-hemispherical, yellowish-green, 4.0–5.0 × 3.8–5.4 mm, dorsally compressed, obtuse-rounded at the apex; column cylindrical, ca. 1.0 mm; anther cap galeate with two chambers, ca. 0.8 × 0.5 mm; rostellum bilobed; pollinarium ca. 0.3 mm long; pollinia 2, ca. 0.3 × 0.2 mm, yellow, subglobular, porate; stigma deeply sunken, inverted V-shaped, ca. 0.5 mm long, white; rostellum bilobed. Fruits not mature.

Distribution and habitat.

Gastrochilus jiuzhaigouensis is currently known only from Wuhuahai, Jiuzhaigou County, Sichuan Province, Southwest China (Fig. 4 ). It is epiphytic on dieback tree branches on the bank of a lake of trees in the border of subalpine mixed coniferous and deciduous broadleaf forest dominated by Pinus tabuliformis Carrièreat at elevational range between 2400 and 2500 m. Other common accompanying broadleaf trees include Acer stachyophyllum subsp. betulifolium (Maxim.) P. C. De Jong , Fraxinus chinensis Roxb. , Prunus tomentosa Thunb. , and Quercus mongolica Fisch. ex Ledeb. , among others. And in shrub layer Berberis amurensis Rupr. can reach a height of two to three meters.

Phenology.

Flowering from March to April.

Etymology.

Its specific epithet is taken from name of Jiuzhaigou World Heritage Site, where the type specimen of this new orchid is located. Jiuzhaigou is also the name of the famous Jiuzhaigou National Park and the county name in Northwest Sichuan. It is therefore the Chinese name that is proposed as jiu zhai gou peng ju lan (九寨沟盆距兰).

Additional specimens examined

( paratypes). China • Sichuan: Jiuzhaigou, Wuhuahai , on lake bank of broadleaf tree at the border of subalpine coniferous mixed forest, on tree branches, elev. ca. 2,478 m, in flower, 23 April 2024, Jun-Yi Zhang & Da-Lin Zhu ZJY 197 ( CDBI!) .

Other specimens examined.

Gastrochilus bernhardtianus . China • Yunnan: Lijiang Prefecture, Yulong County, Yunshanping , elev. ca. 3308 m, in cold-temperate, evergreen conifer forest, in flower, 20 May 2020, J. - D. Ya et al. 20 CS 19022 ( holotype KUN).

Gastrochilus balangshanensis . China • Sichuan: Wenchuan, Balangshan, Yinchangou , mixed coniferous forest, on tree branches, elev. ca. 2,260 m, in flower, 19 April 2023, Jun-Yi Zhang & Yue-Hong Cheng ZJY 185 ( holotype: CDBI!); ibid. loc., mixed coniferous forest, on tree trunk, elev. ca. 2300 m, in flower, 19 April 2023, Jun-Yi Zhang & Yue-Hong Cheng ZJY 186 ( CDBI!); ibid. loc., mixed coniferous forest, on tree branch, elev. ca. 2315 m, in fruit, 22 July 2024, Jun-Yi Zhang & Yue-Hong Cheng ZJY 204 ( CDBI!).

Figures

Figure 2. Habitat and habit of Gastrochilus jiuzhaigouensis in situ. A, B. Habitat; C – E. Flowering plants of G. Jiuzhaigouensis growing on tree branches. [Images A – E. Photographed by Da-Lin Zhu].

Figure 3. Gastrochilus jiuzhaigouensis. A. Flowering plant; B. Leaves (B 1: front view, B 2: abaxial view); C. Flowers, front view; D. Flowers, abaxial view; E. Dissection of a flower (E 1: dorsal sepal; E 2-3: lateral sepals; E 4-5: petals; E 6: labellum); F. Anther cap; G. Pollinarium with pollinia; H. Raceme, lateral view; I. Labellum, lateral view. [Images A – I. photographed by Jun-Yi Zhang].

Figure 4. Distribution map of Gastrochilus jiuzhaigouensis and five related species in Gastrochilus; G. jiuzhaigouensis, G. balangshanensis, G. bernhardtianus, and G. obovatifolius are grouped in G. sect. Microphylli, and G. nanchuanensis in G. sect. Caespitosi.