Cymbidium bavuongii Aver. & 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 : 28-31

Cymbidium bavuongii Aver. & V.C.Nguyen , sp. nov.

( Fig. 4 .)

Diagnosis: —The new species differs from the morphologically closest C. eburneum and C. maguanense in insignificant narrowly fusiform pseudobulbs 1.6–3 cm long, linear leaves 4–6.5 mm wide, peduncle 8–14 cm long, smaller flowers with yellowish green sepals 4–4.6 cm, glabrous lip 3.2–4 cm long, narrow petals 5–7 mm wide, median lip lobe triangular cordate, 9.5–11.5 mm long and wide, disk with low fleshy longitudinal keel obscurely 4-dentate at apex, column 3.2–3.4 cm tall, densely hairy at front in basal third.

Type: — VIETNAM. Type herbarium specimen was prepared from cultivated plants on 22 August 2023, L. Averyanov, Nguyen Van Canh, T. Maisak, AL 2241 (holotype LE: LE 01232953 https://en.herbariumle.ru/?t=occ&id=192246, isotype LE 01232954 https:// en.herbariumle.ru/?t=occ&id=192247), originally collected in Dak Lak Province, Chu Yang Sin National Park, Chu Yang Sin Mt., primary broad-leaved evergreen forest at elevation of 1600–1700 m a.s.l., epiphyte on tall mossy tree, not common. August 2019, Nguyen Van Canh s.n., photos of plants used for preparation of the type specimen ( LE: LE 01124312 https://en.herbariumle. ru/?t=occ&id=186936, LE 01124313 https://en.herbariumle.ru/?t=occ&id=1869370, LE 01255215 https://en.herbariumle.ru/?t=occ&id=241569).

Description:—Epiphytic or lithophytic herb with densely clustering pseudobulbs. Pseudobulbs narrowly fusiform, often slightly flattened, (1.6)2–2.6(3) cm long, (0.8)0.9–1.2(1.4) cm wide, entirely covered by leaf sheaths, at base with 2–3 subulate, brownish purple, coriaceous, acute cataphylls, (1.2)1.6–3.2(3.8) cm long, 10– 2.5 mm wide (when flat). Roots thick, fleshy, white to yellowish brown, 3–3.5 mm in diameter. Leaves (3)4–8(9), articulate, base distichous, linear, arching, to (15)20–40(45) cm long, (4)4.5–6(6.5) mm wide, acute. Inflorescence arising from base of pseudobulb, ascending to erect; peduncle (8)10–12(14) cm long, at base with (3)4(5) reddish brown, imbricate, conduplicate, cymbiform, acute bracts, at apex with 1–2 flowers opening simultaneously. Floral bracts pale green, triangular, 3.2–3.4 mm long and wide, acute. Pedicel and ovary pale yellowish to dull pink, terete, narrowly obconoid, 2.2–2.6 cm long, 2.8–3.2 mm in diameter. Flowers not widely opening, (2.2)2.5–3(3.2) cm in diameter; petals and sepals light yellowish green with pink tint in basal half, obtuse to acute; lip uniform rose pink with light greenish center, callus distally white; column white tinged pale pink, light yellow at front near the base. Sepals straight, forward directed, broadly oblanceolate, obtuse, (4)4.2–4.4(4.6) cm long, (8)9–11(12) mm wide, lateral sepals oblique. Petals oblanceolate, oblique, acute, as long as sepals, (5)5.5–6.5(7) mm wide. Lip obtriangular to obovate in outline, (3.2)3.5–3.8(4) cm long, 1.8–2.2 cm wide, 3 lobed, at base fused to basal margins of column for 5.5–6.5 mm; loosely clasping column, side lobes erect, half-ovate, 1.8–2 cm long, 7–8 mm wide, apex rounded; median lobe triangular cordate, undulate along the margin, (9.5)10–11(11.5) mm long and wide, obtuse to rounded at apex, strongly recurved to revolute; disk glabrous to finely papillate, with low fleshy longitudinal keel 4.5–5 mm wide, extending from base of lip to base of median lobe, at apex obscurely 4-dentate. Column erect, at apex slightly forward curved, 3.2–3.4 cm tall, 4.5–5.5 mm wide, narrowly winged, in basal third at front with concave area densely hairy with long white hairs; stigma obscurely obtriangular. Operculum helmet-shaped, glossy glabrous, at front with very short, broad beak. Pollinia 2, ovoid, with short, broad, common caudicle and viscidium. Fruits not seen.

Etymology: —The species is named by L. Averyanov and Nguyen Van Canh after Mr. Truong Ba Vuong, a distinguished expert in the taxonomy of orchids in eastern Indochina.

data from personal observations, as well as Lindley 1847, Liu 1996, Pearce & Cribb 2002, Liu et al. 2006, and Chen et al.

2009).

Ecology and phenology: —Epiphyte or lithophyte, primary broad-leaved evergreen submontane and montane forests on granite at elevation of 1600–1700 m a.s.l. Flowers in cultivation in August–September.

Distribution: — Vietnam, Dak Lak Province (Chu Yang Sin National Park).Probably endemic of Central Highlands in southern Vietnam.

Conservation status: —This species is known from a single site by a single extremely small population. This population discovered in Chu Yang Sin National Park includes few mature samples. The AOO is less than 10 km 2. Despite official protection of the territory harboring a single species population, it is still influenced by selective logging and a decrease in habitat quality. This is inferred as continuing decline in quality of habitat. The number of locations is one accordingly. Additionally, taking into consideration the high demands for the Cymbidium species on the market of wild ornamental plants, this species need to be protected. Accordingly, following the formal criteria of the IUCN Red List (2024), it is assessed as Critically Endangered (CR) B2ab(iii).

Notes: —In plant habit and floral morphology Cymbidium bavuongii is most close to C. eburneum Lindley (1847 tab. 67) and C. maguanense Liu (1996: 412) , but differs in a series of characters listed in details in Table 1.

Additionally studied specimens (paratypes):— VIETNAM. Dak Lak Province, Cu D’Ram Commune, Krong Bong District, Chu Yan Sin Mountain, 28August 2023, Truong Ba Vuong, Loc Bao Sang, BV 1901 ( VNM 00070007), BV 1902 ( VNM 00070009), photos of plants used for the preparation of paratypes LE ( LE 01255145 https://en.herbariumle. ru/?t=occ&id=228647).

Figures

FIGURE 4. Cymbidium bavuongii. A. Flattened flowering plant used for the preparation of the type specimens. B. Apical part of inflorescence. C. Intact flower, frontal view. D. Floral bract, adaxial side. E. Separated flower, view from below. F. Flattened pedicel, column, sepals and petals (adaxial side). G. Pedicel, ovary, lip, and column, view from above and from below. H. Lip, view from different sides. I. Flattened lip, adaxial side. J. Flattened epichile and distal part of disc callus, adaxial side. K. Column, view from different sides. L. Basal half of column, half-side and front view, showing indumentum. M. Apex of column with operculum, side and front view. N. Operculum, view from different sides. O. Pollinarium, view from different sides. Photos by L.Averyanov, from the specimen AL2241 used for the preparation of the type specimens. Photo correction and design by L. Averyanov and T. Maisak.