Cymbidium sangii Aver. & V.C.Nguyen, 2023

Averyanov, Leonid V., Nguyen, Van Canh, Truong, Ba Vuong, Nguyen, Khang Sinh, Nguyen, Cuong Huu, Maisak, Tatiana V., Doan, Nga Thi, Nguyen, Tuan Hoang, Pham, Van The, Dat, Pham Thi Thanh, Thai, Tran Huy, Nguyen, Van Khuong & Trinh, Ngoc Bon, 2023, New orchids in the flora of Vietnam VI (Orchidaceae, tribes Arethuseae, Cymbidieae, Diurideae, Epidendreae, Vandeae, and Vanilleae), Phytotaxa 597 (2), pp. 87-110 : 96-99

Cymbidium sangii Aver. & V.C.Nguyen , sp. nov. ( Fig. 5 )

Type:— VIETNAM, Lam Dong Province, Di Linh District , evergreen broad-leaved forest at an elevation of 800–900 m a.s.l., terrestrial herb, locally common, 22 October 2019, Nguyen Van Canh, AL 1134 (holotype LE01168112 https://en.herbariumle. ru/?t=occ&id=133898, isotypes LE01066643 https://en.herbariumle.ru/?t=occ&id=133881, LE01066644 https://en.herbariumle. ru/?t=occ&id=133882, analytical photos from living plants used for the preparation of the type specimen LE01061322 https:// en.herbariumle.ru/?t=occ&id=12436, LE01088315 https://en.herbariumle.ru/?t=occ&id=46953) .

Paratypes:— VIETNAM, herbarium specimen is prepared from a cultivated plant on 1 September 2022, L. Averyanov , T. Maisak, AL 1134 .1 originated from a clone of the plant used for the preparation of the type specimens (herbarium voucher specimen LE01169533 https://en.herbariumle.ru/?t=occ&id=142651, analytical photos LE01123538 https:// en.herbariumle.ru/?t=occ&id=141845) .

Herb terrestrial, perennial, rosulate, rhizomatous. Stem erect, with (1)2–3(4) imbricate, cuneate, conduplicate cataphylls and 2–3 leaves; swelling at the base in form of an erect, epigeous, green, conoid pseudobulb (3.5)4–4.5(5) cm tall, (1.2)1.4–1.8(2) cm in diameter; naked with age; all stems densely clustered each other on a very short plagiotropic rhizome; with a dense nest of numerous thick, fleshy, white to dull grey, flexuose roots (5)6–7(8) mm in diameter. Cataphylls narrowly triangular to cuneate, acute to acuminate, (4)5–7(8) cm long, (0.8)1.2–2(2.4) cm wide, grassy greenish, becoming light gray brownish, papyraceous, and eventually fibrous with age. Leaves sessile, arching, dark glossy green, rigid or coriaceous, conduplicate, linear to narrowly lanceolate, (40)50–70(80) cm long, (1)1.2–2.8(3) cm wide, obscurely articulate at the base, tapering into an acute apex, evergreen around the year. Inflorescence lax erect raceme, (40)45–60(65) cm tall; peduncle arising from the base of pseudobulb, light grassy green, (15)20–27(30) cm long, with (3)4–5(6) scarious, lanceolate, acute, sterile bracts; rachis (18)20–30(35) cm long with (5)8–16(18) spirally arranged flowers; floral bracts pale green, narrowly triangular-lanceolate, acute, (0.8)1.2–1.6(2) cm long. Pedicel and ovary pale green, slender, at a wide angle to the rachis, (1.2)1.5–2(2.4) cm long, (1)1.2–1.4(1.6) mm in diameter, ovary slightly broadening distally, shallowly ribbed. Flowers widely opening, odorless, (7)8–9(11) cm across; sepals and petals light yellowish green, with one longitudinal purple brownish stripe, sometimes with few unclear purplish spots near the base; lip very light yellowish to almost white, with purple-brown marks and spots; column very light yellowish to almost white, with many longitudinal purple brown streaks at front; anther cap pale yellow. Sepals subsimilar, spreading, narrowly lanceolate to lanceolate, (3.8)4–5.4(5.6) cm long, (4.5)5(5.5) mm wide, 3-veined, acute to acuminate; lateral sepals slightly oblique, twisted at apex. Petals broader than sepals, spreading or slightly forward directed, broadly oblanceolate, slightly oblique, 5-veined, acute, (3.2)3.4–4(4.2) cm long, (6)7–8(9) mm wide. Lip narrowly oblong in outline, not fused to the column base, (2.3)2.4–2.7(3) cm long, (1)1.1–1.2(1.3) cm wide in widest part, 3-lobed; lateral lobes suberect, almost semicircular (2)2.2–2.6(2.8) mm tall, (6.5)7–8(8.5) mm broad; median lobe oblong, more than twice longer than side lobes, (1.6)1.8–2(2.2) cm long, (5)6–7(8) mm wide, strongly recurved, finely papillose; disk with 2 longitudinal glabrous keels extending from the middle of epichile to the base of median lobe, rising and connivent distally, forming an almost close tube. Column stout and short, slightly curved, (1)1.1–1.2(1.3) cm tall, slightly broadening toward the apex, with a small, concave stigma at the front. Anther cup hemispheric, 2.8–3 mm across, truncate at front. Pollinia 4, in 2 pairs, dull yellow, obscurely triangular, flattened, 1–1.2 mm across, with a small scarious triangular viscidium. Fruits erect, cylindric capsules, 3–3.5 cm long, about 6 mm in diameter, on a stalk 6–8 mm long.

Ecology and phenology:—Perennial terrestrial herb. Primary and old secondary broad-leaved evergreen forests on granite at an elevations of 800–900 m a.s.l. Locally common. Flowers in July–November.

Distribution:— VIETNAM, Lam Dong Province (Lac Duong District). Endemic.

Conservation status:—Formally, the species may be estimated as globally Critically Endangered, CR: B1a,b(i-iii,v)+ 2a,b(i-iii,v); D. Available observations indicate that the species meets the following IUCN Red List categories and criteria ( IUCN 2022): only one population was discovered, with the extent of occurrence (EOO) much less than 100 km 2 (B1a) and the area of occupancy (AOO) surely less than 10 km 2 in one known location (B2a); observed and expected continuing decline (b) of the extent of occurrence (i), the area of occupancy (ii), area, extent, and quality of habitat (iii), and the number of mature individuals (v); the population is very small, with the estimated number of mature individuals less than 50 (D).

Notes:—The species is remarkable for its large flowers with an unusually long lip. Morphologically, it is most similar to C. kanran Makino (1902: 10) , but differs in pseudobulbs with 2 (rarely 3) dark green, rigid, or coriaceous leaves, 1–3 cm wide (vs. pseudobulbs with 3–7 grassy green, leathery leaves, 9–17 mm wide), inflorescence distinctly longer than leaves bearing 5–18 flowers (vs. inflorescence as long as leaves, bearing 5–12 flowers), median lip lobe 16–22 mm long, 4–8 mm wide, more than twice longer than side-lobes (vs. median lip lobe 11–16 mm long, 8–12 mm wide, as long as side-lobes, or little longer), and shorter column, 10–13 mm long (vs. column 10–17 mm long). In the coloration of flowers, the new species is similar to C. munronianum King & Pantling (1895: 338) , but has sepals, petals, and a lip twice as long, or longer. The new species has a stout, erect inflorescence with numerous widely opening attractive flowers and represents interest for cultivation as an ornamental plant perspective for breeding and further selection.

Figures

FIGURE 5. Cymbidium sangii Aver. &V.C.Nguyen, sp. nov. A. Flowering plant in cultivation.B. Intact inflorescence.C, D. Pseudobulbs, roots and basal part of leaves. E. Flattened plant parts. F. Flattened floral parts. G. Flattened lip, adaxial and abaxial side. H. Flattened lip hypochile. I. Column and anther cap, view from different sides. J. Anther cap, view from different sides. K. Pollinarium, frontal view and view from above. All photos were made from the plant used for the preparation of the specimen, V.C. Camh, AL 1300, by L. Averyanov, with photo correction and design by L. Averyanov and T. Maisak.