Micropera vietnamensis Aver., Vuong & V.C.Nguyen, 2025

Averyanov, Leonid V., Nguyen, Van Canh, Vuong, Truong Ba, Quang, Bui Hong, Nguyen, Khang Sinh, Le, Tuan Anh, Binh, Tran Duc, Maisak, Tatiana V. & Nguyen, Cuong Huu, 2025, New orchids in the flora of Vietnam X (Orchidaceae, Orchidoideae, tribe Orchideae, Epidendroideae, tribes Gastrodieae, Arethuseae, Cymbidieae, and Vandeae), Phytotaxa 681 (1), pp. 20-54 : 44-45

Micropera vietnamensis Aver., Vuong & V.C.Nguyen , sp. nov.

= Micropera mannii auct . non Tang & F.T.Wang (1951: 94): Averyanov et al. (2022b: 52, fig. 6A–D).

Diagnosis: — Micropera vietnamensis morphologically is most close to M. mannii , from which well differs in hairy rachis 8–13 cm long bearing to 35 flowers, twice longer pedicel and ovary 7–11 mm long, almost purple, distinctly larger flowers 9–11 mm across, broadly oblanceolate to oblong narrowly obovate obtuse sepals and petals 5–8 mm long, 1.2–1.8 mm wide, lip side-lobes obliquely truncate to roundish, and rostellum straight, as long or longer than column.

Type: — VIETNAM. Dak Lak Province: herbarium specimen prepared from cultivated, wild collected plants, 29 May 2022, L. Averyanov, N. V. Canh, T. Maisak, AL 1339 (holotype LE 01168977 https://herbariumle. ru/?t=occ&id=142645, analytical photos LE 01123411 https://en.herbariumle.ru/?t=occ&id=137201).

Description:—Herb monopodial perennial epiphytic. Stem rigid, pendulous, simple or few branching near the base, (12)15–30(35) cm long, covered by leaf sheaths throughout, leafy in apical half, with few light gray roots near base. Leaves sessile with distinct articulation at the base; leaf blade rigid, lorate lanceolate, distinctly conduplicate, keeled below, gradually tapering to shortly bifid apex, (7)8–14(16) cm long, (0.8)0.9–1.1(1.2) cm wide. Inflorescences placed opposite leaf base, lax raceme, (10)12–16(17) cm long; peduncle straight to arching, 2–4 cm long, sheathed at base; rachis straight to distinctly zig-zag, with sparse brownish scurfy hairs, (8)10–12(13) cm long; floral bracts narrowly triangular, acute, 2.5–3 mm long. Flowers (9)9.5–10.5(11) mm across; sepals and petals light pink to purple, often with unclear irregular purple marks; lip pink to purple with white apex. Pedicel and ovary greenish to pink, hairy with brownish scurfy hairs, (7)8–10(11) mm long, 0.8–1 mm in diameter. Sepals and petals broadly oblanceolate to oblong narrowly obovate, obtuse, spreading, (5)6–7(8) mm long, 1.2–1.8 mm wide, lateral sepals shortly connate with lip base, petals little narrower. Lip obscurely 3-lobe, fleshy, narrowly obovoid, bailer-shaped in outline, (4)4.5–5.5(6) mm long, narrowing to the base, distally broadening, deeply saccate, at right angle to the ovary; side-lobes obliquely truncate to roundish, erect, with incurved front corner; median lobe minute, broadly triangular. Column foot-less, 1.4–1.6 mm tall, twisted, with large, straight, narrowly triangular, oblique rostellum. Operculum hemispheric, 0.6–0.7 mm in diameter. Fruits fusiform to elongate cylindrical, stalked, longitudinally ridged capsule (2)2.4(2.8) cm long, 2.3. 2 mm in diameter (not ripe).

Ecology and phenology: —Epiphyte in lowland evergreen broad-leaved forests. Flowers in May–June.

Distribution:— Vietnam (Dak Lak and Quang Binh provinces). Endemic to central Vietnam.

Conservation status:— Micropera vietnamensis is presently known from two documented populations located in Dak Lak and Quang Binh provinces distant from each other for about 600 km. The area of both populations has no official protection and experienced currently the wide uncontrolled deforestation. This can be inferred as continuing decline in quality of habitat, number of locations is 2 and AOO is less than 10 km 2. The conservation status of this species is thus estimated as Endangered B2a(iii) following formal criteria proposed by the IUCN (2024).

Notes: —Plants discovered in Vietnam surely resembles Micropera mannii ( Hooker 1890: 36) Tang & F.T.Wang (1951: 94) known from Bhutan and NE India (Assam, Meghalaya, Nagaland, Arunachal Pradesh, Sikkim, West Bengal) why they were erroneously identified as this species two years ago ( Averyanov et al. 2022b). Meanwhile, the study of additional materials reveals a series of characters, which clearly segregate Vietnamese specimens from Indian plants, namely: rachis 8–13 cm long, bearing to 35 flowers, hairy with sparse brownish scurfy hairs (vs. rachis glabrous, 2–8.5 cm long, bearing less than 18 flowers), pedicel and ovary 7–11 mm long (vs. pedicel and ovary 3–6 mm long), flowers 9–11 mm across, almost purple except white lip apex, lip base uniform bright purple (vs. flowers 6–7 mm across, almost white with yellowish lip, lip base with two distinct deep purple stripes), sepals and petals 5–8 mm long, 1.2–1.8 mm wide, broadly oblanceolate to oblong narrowly obovate, obtuse (vs. sepals and petals 3–4.5 mm long, 0.8–1.2 mm wide, obovate, roundish to truncate at apex), lip side-lobes obliquely truncate to roundish (vs. lip side lobes obtuse to acute), and rostellum straight, as long or longer than column itself (vs. rostellum sigmoid, down curved shorter than column). Illustrations of plants regarded here as a new species were published earlier ( Averyanov et al. 2022b: 52, fig. 6A–D). under the name C. mannii . The area of the new species distant from closest locations of C. mannii in NE India for about 1600 km.

Additional studied specimen (paratype):— VIETNAM, Quang Binh Province: Minh Hoa District, herbarium voucher specimen prepared from cultivated wild collected plant, 11 November 2023, L. Averyanov, Nguyen Van Canh, Truong Ba Vuong, T. Maisak, AL2582 (LE: LE01253890 https://en.herbariumle.ru/?t=occ&id=213870, analytical photos LE01124632 https://en.herbariumle.ru/?t=occ&id=207912).