Schoenorchis hungii Aver., V.C.Nguyen & Vuong, 2022

Averyanov, Leonid V., Thai, Tran Huy, Truong, Ba Vuong, Nguyen, Van Canh, Nguyen, Tuan Hoang, Maisak, Tatiana V., Nguyen, Khang Sinh & Nguyen, Van Khuong, 2022, New orchids in the flora of Vietnam (Orchidaceae, Aeridinae), Phytotaxa 555 (2), pp. 113-135 : 127-128

Schoenorchis hungii Aver., V.C.Nguyen & Vuong , sp. nov.

( Fig. 7 )

Type: — VIETNAM. Type herbarium specimen prepared on 25 April 2020 by L. Averyanov, T. Maisak, AL 410 from cultivated plants collected in Lam Dong Province, Bidoup Nui Ba National Park, evergreen broad-leaved forest, at 1500–1600 m a.s.l. on 2 September 2018, Nguyen Van Canh (holotype LE01068479 https://en.herbariumle.ru/?t=occ&id=16592) .

Authentic photos: — VIETNAM. Photos are made on 25 April 2020 by L. Averyanov, T. Maisak, AL 410 from cultivated plants collected in Lam Dong Province, Bidoup Nui Ba National Park, evergreen broad-leaved forest, at 1500– 1600 m a.s.l. on 2 September 2018, Nguyen Van Canh s.n. ( LE 01122887 https://en.herbariumle.ru/?t=occ&id=99509, LE 01073077 https://en.herbariumle.ru/?t=occ&id=15213).

Etymology: —The species name refers to Mr. Do Tuan Hung for his great contribution to the conservation of Vietnamese orchids.

Description:—Herb miniature monopodial, branch and canopy epiphyte. Stem simple, suberect or ascending (3)4–6(7) cm long, leafy in apical two thirds, with internodes (1.8)2–4(4.5) mm, leafless in basal part, (2)2.5(3) mm in diameter, with few, flexuose whitish roots near the base. Leaves grassy green, finely rugose, sessile, very fleshy, spreading at a wide angle to stem, arching, subterete, adaxially grooved, (1.5)2–3(3.5) cm long, (1.8)2–2.8(3) mm in diameter, acute, slightly constricted near of articulation with leaf sheath; leaf sheaths equitant, rigid, verruculose, completely covering the stem. Inflorescence axillary, suberect or ascending raceme, rarely 1–2 branched panicle, (5)5.5–6.5(7) cm long, scape and rachis light grassy green; scape (2)2.5–3.5(4) cm long, more or less straight; rachis straight or somewhat arching, thin, slightly angled, (1)2–3(3.2) cm long, with many spirally arranged, subdense flowers, distant at (0.6)1(1.4) mm. Floral bracts relatively large, white, light green along median rib, rhomboid, (1.8)2–2.5(2.7) mm long, (1.7)1.8–2(2.2) mm wide, shortly fimbriate along the margin, cuspidate, with prominently attenuate apex. Pedicel and ovary light green, (1.2)1.3–1.4(1.5) mm long, about 0.4–0.5 mm in diameter, terete, glabrous. Flowers odorless, tubular, with recurved apical third of sepals and petals, (1.6)1.8–2(2.2) mm across; sepals white, median sepal with purple apex, lateral sepals with purple median longitudinal stripe; petals entirely bright purple, lip including spur snow-white, column green, anther cap and pollinia bright yellow. Sepals narrowly ovate, little concave, dorsally slightly carinate, blunt to roundish at apex, (1.5)1.6–1.8(1.9) mm long, 0.6–0.7 mm wide, lateral sepals slightly oblique. Petals oblong broadly lanceolate, rounded to blunt at apex, as long as median sepal, 0.3–0.4 mm wide, distally strongly recurved. Lip spurred, (2.6)2.8–3(3.2) mm long (from spur apex to the apex of median lobe), almost entire; median lobe very fleshy, narrowly obovate (when look from below), rhomboid (from side view), 1.4–1.6 mm long, 0.5–0.6 mm wide, round at apex, straight, forward directed; at the base with 2 massive fleshy lateral longitudinal rollers almost completely closing entrance to the spur. Spur shortly conoid, slightly upcurved, parallel to ovary, (1)1.1–1.2(1.3) mm long, about 0.5 mm wide, with no longitudinal septum or back-wall callus inside. Column stout, very short, 0.2–0.3 mm tall and wide, with no wings; rostellum very small, broad, forward directed; stigma obscurely triangular to roundish. Anther cap, hemispherical, 0.2–0.3 mm in diameter, with prominent triangular, obtuse, forward directed beak about 2 mm long. Pollinarium 1, with 2 pollinia, flat oblong stipe (tegula) and flat oblong narrowly ovate viscidium. Pollinium ovoid or globular, splitting into 2 unequal hemiovoid lobes. Fruit unknown. All measurements were taken on fresh floral parts, which become about 1/3 smaller after exsiccation in process of herbarium specimen preparation ( Averyanov et al. 2019e).

Habitat, phenology and conservation status: —Miniature branch and canopy epiphyte on tall mossy trees. Evergreen broad-leaved submontane and montane forests at 1000–1800 m a.s.l. Rare. Flowers in April–May, October– November. Suggested IUCN Red List status – EN.

Distribution: — VIETNAM, Lam Dong Province (Lac Duong and Lam Ha districts). Endemic.

Notes: —The new species, like Schoenorchis tatonii Aver. in Averyanov et al. (2019: 295)recently described from the same area, represents one another local sympatric race of the widespread S. gemmata ( Lindley 1838: 50) J.J. Smith (1912: 100) endemical to the mountain area known in Vietnamese geography as Central Highlands, or Tay Nguyen Plateau (Averyanov et al. 2003). In its morphology the new species clearly differs from S. gemmata in the small dimensions of the whole plant, with the stem 3–7 cm long having internodes (1.8)2–4(4.5) mm (vs. stem 5–15 cm long, with internodes 7–15 mm long), fleshy, subterete leaves 1.5–3.5 cm long and 1.8–3 mm in diameter (vs. distinctly dorso-ventrally flattened, conduplicate, more or less flat, 5–10 cm long, 5–12 mm wide), inflorescence simple, rarely 1–2 branched, 5–7 cm long (vs. inflorescence almost always branching, 8–15 cm long), floral bracts relatively large, rhomboid, cuspidate, enveloping pedicel and ovary, reaching middle of median sepal, much longer than ovary, finely fimbriate along the margin (vs. floral bract small, triangular, acute, not enveloping and twice shorter than pedicel and ovary, with entire margin), pedicel and ovary light green, 1.2–1.5 mm long (vs. pedicel and ovary green to dirty violet, about 3 mm long), flowers (1.6)1.8–2(2.2) mm across, sepals and petals distinctly recurved in apical half (vs. flowers 3–4 mm across, sepals and petals straight or slightly recurved at apex), sepals white with purple apex of median sepal and light purple stripe on lateral sepals, petals bright purple, lip including spur white (vs. sepals and petals entirely dull lilac violet, lip white often with lilac violet tint), sepals and petals 1.5–1.9 mm long (sepals and petals 2–2.5 mm long), lip almost entire, narrowly obovate, hardly broadening from hypochile, 0.5–0.6 mm wide (vs. obscurely lip 3-lobed, median lobe broadly obovate or flabellate rhomboid, twice broader than hypochile, 1–1.2 mm wide), spur 1–1.3 mm long, about 0.5 mm wide (spur about 2 mm long and 1.5 mm wide), and column 0.2–0.3 mm tall (vs. column 0.6–0.8 mm tall).

Schoenorchis hungii is undoubtedly very rare. Up to now it was collected only in three close localities in the densely populated and currently highly urbanized Lac Duong and Lam Ha districts of Lam Dong Province in the center of southern Vietnam. Taking into consideration the vast deforestation in both provinces the estimated extent of occurrence (EOO) is probably limited by the territory of Bidoup – Nui Ba National Park. In this connection, it cannot be larger than 700 km 2 area of occupancy (AOO) is 12 km 2 in terms of IUCN (2019). According to available data and following to criteria proposed by IUCN the conservation status of the new species may be preliminarily estimated as Endangered – EN B2ab(iii) ( IUCN 2019).

Studied specimens: — VIETNAM, herbarium specimen prepared on 10.11.2019 by L. Averyanov, AL 1221 from cultivated plant collected in Lam Dong Province, Lam Ha District, evergreen broad-leaved submontane forest at elevation about 1000 m a.s.l., epiphyte on tall trees, Ngo Quang Dang s.n, 28 October 2019 LE01066612 https:// en.herbariumle.ru/?t=occ&id=12381. VIETNAM, Lam Dong Province, Bidoup Nui Ba National Park, Bidoup Mountains, primary evergreen broad-leaved forest at elevation 1700–1800 m a.s.l., epiphyte on tall mossy tree, not common. 2019, Nguyen Van Canh , AL 1113, LE01167750 https://en.herbariumle.ru/?t=occ&id=133079.

Figures

FIGURE 7. Schoenorchis hungii. A. Intact flowering plant. B. Flattened flowering plant. C. Portion of inflorescence with different magnification. D, E. Flower buds with intact floral bract. F. Flattened floral bract. G. Intact flowers, frontal and side views. H. Intact flower, view from below. I. Flower with median sepal removed, view from above. J. Flower with lateral sepal removed, side view. K. Flowers with lateral sepal and petal removed, side view. L. Flattened sepals and petals. M. Separated lip and column, view from above. N. Base of lip and column, view from above. O. Sagittal section of the flower. P. Anther cap, view from different sides. Q. Pollinarium, view from different sides. All photos, photo correction and design by L. Averyanov and T. Maisak (plant used for the preparation of the type herbarium specimen AL 410).