The length of nrITS matrix was 792 bp including 262 parsimony-informative sites and for
Maximum Likelihood tree of
The phylogenetic analyses indicate that
China. Yunnan Province (云南), Xishuangbanna (西双版纳), Mengla County (勐腊县) epiphyte on the tree trunk, 1620 m elev., 23Nov 2021, Zhengwei Wang, Xiaochen Li, Yu Zhang& Zhijin Wu, WZW04247 (holotype:
Morphology of
Epiphytic herbs. Roots slender, flexuose. Pseudobulbs clustered, ovoid-fusiform, slightly compressed laterally, 1–2 × 0.5–1 cm, upper half with 4–5 widely spaced leaves. Leaf blade ovate-oblong, 1.8–2.3 × 0.8–1.2 cm, apex acuminate, base contracted into a short petiole, articulate, margins of their apical half slightly crispate. Peduncle 7–10 cm long, with several sterile bracts 2–5 mm long; raceme with 7–10 flowers arranged in zigzag manner. Floral bracts broadly ovate with cordate base, 2–3 × 1–1.5 mm, acute. Flowers greenish-orange; pedicel and ovary ca. 7 mm long. Dorsal sepal broadly ovate with cordate base, 3.2–5 × 3–3.6 mm, 1-veined, abaxially carinate, apex acute; lateral sepal oblong-ovate or ovate-lanceolate, 5–6 × ca. 0.6 mm long, abaxially slightly carinate. Petals narrowly linear, 3–4 × ca. 0.2 mm; lip elliptic, 2–3 × ca. 1 mm, apex apiculate, base bearing a bituberculate callus, then expanded on each side into a thickened, folded, rounded lobe, with 1 excavation with raised margins between the lobes. Column straight, ca. 2 mm long, with a pair of subtriangular, obtuse wings on each side near the middle and a ridge on the back of the column. Anther cap hemispherical, pale yellow; pollinia 4 in 2 pairs with one pollinium of each pair smaller than the other, waxy, brownish, with minute apical viscidium.
Phenology: Flowering in November–December.
It is found on tree trunks on a limestone ridge-top evergreen broad-leaved forest at an elevation of 1500–1700 m in Mengna County, Xishuangbanna Autonomous Prefecture, Yunnan Province, People’s Republic of China. The habitat presents a tropical monsoon climate.
The species epithet refers to the large and conspicuous dorsal sepal of the flower.
Comparison of
| Characters |
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|
|
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|---|---|---|---|---|---|
| Pseudobulbs | oblong or cylindrical-fusiform 5–9 3–5 mm | ovoid, 8–10 mm long | ovoid-fusiform, slightly compressed 1.5–2.5 cm × 6–10 mm | subcylindrical or ± spindle-shaped, 1.8–5 cm × 3–6 mm | ovoid-fusiform, slightly compressed, 1–2 cm × 0.5–1 cm |
| Leaf | 2 or 3, margin flat | 3 or 4, strongly crisped-margined | 3 or 4, apical half slightly crisped-margined | 3 or 4, margin slightly serrate | 4 or 5, apical half slightly crisped-margined |
| Scape | 2–5 cm, several to 10-flowered, flowers white | 5–10 cm long, with 10–15 flowers, flowers yellow, | 10–13 cm, more than 10-flowered, flowers orange | 7–18 cm, 10–50-flowered, flowers pale green or greenish-yellow | 7–10 cm, more than 10-flowered, flowers greenish-orange |
| Bracts | ovate-lanceolate, 2–3 mm | ovate-lanceolate, 1.5–3.5 mm | lanceolate, 2–3 mm | lanceolate, 3–5 mm | broadly ovate, 2–3 mm |
| Dorsal sepal | ovate-oblong, 2.5–3 × 1.5–1.8 mm | oblong-lanceolate, 3–4 × 0.8–1 mm | narrowly ovate-oblong, 4.8–5.8 × ca. 1.6 mm | oblong or elliptic-oblong, ca. 4 × 1.8 mm | broadly ovate, ca. 3.2–5 ×3–3.6 mm |
| Petals | narrowly linear-lanceolate, 2.5–3 × ca. 0.5 mm, entire | narrow linear, 4–5 mm long, Y-shaped | narrowly linear, 5–5.5 × ca. 0.7 mm, entire | narrowly linear, ca. 3.5 × 0.3 mm, entire | narrowly linear, 3–4 × ca. 0.2 mm, entire |
| Lip | broadly elliptic or orbicular, ca. 2.5 mm, base with an orbicular, auriculate, callus-shaped fold on either side, with a concave callus near base | epichile broadly oblong or subsquare, 1.5–2 × 1–1.5 mm, base with two auricles on both sides; claw short, with a fleshy callus centrally near base | broadly obovate-oblong, ca. 4 × 2.7 mm, with two callus-shaped thickened folds, two suborbicular lobes on both sides, centrally with one concave callus near base | broadly elliptic-oblong or broadly ovate-oblong, 2.5–3 mm, with two lateral splits below middle; two suborbicular lobes, centrally with one bilobed callus near base | broadly elliptic, ca. 2–3 mm long, two callus-shaped and thickened folds, base with two oblong lobes on both sides, centrally with one bituberculate callus near base |
| Column | ca. 2.2 mm, two pairs of wings | ca. 1.5 mm, broadly winged with two horn-like appendages | ca. 2 mm, two pairs of wings | ca. 2.8 mm, a pair of wings, each with a retrorse thread | ca. 2 mm, a single pair of subtriangular wings |
The new species was found in a ridge-top evergreen broad-leaved forest on a limestone mountain. Despite numerous surveys in the areas, only six mature individuals were found without fruits or evidence of cross-pollination.
This extremely small effective population occurs in a touristic zone which is a serious threat to the survival of the species. Consequently, the species can be assessed as Critically Endangered (CR, D), based on current information and following IUCN guidelines (