Bulbophyllum bidoupense Aver. et N.V.Duy, 2015

Duy, Nong Van & Averyanov, Leonid V., 2015, Bulbophyllum bidoupense and Schoenorchis hangianae-new species of orchids (Orchidaceae) from southern Vietnam, Phytotaxa 213 (2), pp. 113-121 : 114-117

Bulbophyllum bidoupense Aver. et N.V.Duy , sp. nov. Figs 1A–G , 2

Small short-creeping epiphyte; pseudobulbs 1-leaved, crowded, touching each other, rudimentary, 1.5 – 5 mm across; leaves erect, oblanceolate, fleshy, subterete to broadly crescent at cross section, 2.5 – 8 cm long; inflorescence pendulous lax purple raceme 6 – 20 cm long; pedicel and ovary 1.5 – 2 mm long, sparsely verruculose; flowers purple to dark purple, pendulous, not widely opening; sepals free, broadly lanceolate to narrowly ovate, 5 – 9 mm long, 3-keeled; petals broadly lanceolate, 2.5 – 3 mm long; lip oblong ovate triangular, strongly recurved, adaxially papillose, 2.2 – 2.8 mm long, 0.6 – 1 mm wide; column 1 mm tall, with large 3-lobed stelidia much exceeding anther cap; anther cap hemispheric, 0.5 – 0.6 mm across, at apex truncate, finely erose.

Type: — VIETNAM. Lam Dong province: Lac Duong district, Hon Giao mt., Bidoup Nui Ba national park , canopy epiphyte in broad-leaved, evergreen, humid forest at elev. about 1526 m a.s.l. around point 12°10’28’’N, 108°41’58’’E. 27 May 2014, Nong Van Duy, VTN 1030 (holotype, Herbarium of Tay Nguyen Institute of Scientific Research of Vietnamese Academy of Science and Technology!; isotype, LE!) .

Perennial short-creeping sympodial epiphytic herb. Rhizome short, insignificant, simple or few branching, with erect, densely clustering pseudobulbs. Pseudobulbs 1-leaved, commonly touching each other, very small, rudimentary, dark green, globular to oblate, (1.5 –)2 – 4(– 5) mm in diam., sometime slightly oblique, young enveloped by brownish scarious sheaths, old with fibrous remnants at the base. Leaves sessile, erect, oblanceolate, obtuse, rigid, fleshy, succulent, subterete broadly furrowed, broadly crescent at cross section, (2.5 –)3.5 – 6.5(– 8) cm long, (2 –)3 – 5(– 8) mm wide, (1.5 –)2 – 3(– 4) mm thick. Inflorescence raceme, arising from the base of pseudobulb, (6 –)8 – 18(– 20) cm long, arching to pendulous; scape dark purple, suberect or almost horizontal, (3 –)4 – 8(– 10) cm long, with (1 –)2 – 3 small distant sterile bracts; rachis purple, commonly nodding and pendulous, (3 –)4 – 8(– 10) cm long with many spirally arranged lax flowers. Floral bracts purple to dark purple, almost straight, cuneate, conduplicate, acuminate, (2 –)3 – 5(– 6) mm long, 0.5 – 1 mm wide. Pedicel and ovary purple to dark purple, 1.5 – 2 mm long, sparsely verruculose; ovary obovoid 0.8 – 1.2 mm long; pedicel cylindric, 0.8 – 1 mm long, 0.4 – 0.5 mm in diam. Flowers pendulous, not widely opening; sepals and petals purple to dark purple, sepals with 3, petals with 2 light purple to whitish stripes, lip purple-brown to olive tinged with purple, column and anther cap white. Sepals free, subsimilar, straight, 3-veined, diverging toward their apices, broadly lanceolate to narrowly ovate, acuminate, (5 –)6.5 – 8.5(– 9) mm long, 1.6 – 2.2 mm wide, dorsally with 3 distinct keels, lateral sepals slightly oblique and larger. Petals straight, forward directed, oblong broadly lanceolate, 1 - veined, acute, 2.5 – 3 mm long, 0.5 – 0.8 mm wide. Lip oblong ovate triangular, blunt, strongly recurved, conduplicate in basal half, with indistinct ears at base, densely papillose on adaxial surface, 2.2 – 2.8 mm long, 0.6 – 1 mm wide, joined with column foot apex by movable articulation. Column erect, cylindrical, 1 mm tall, 0.6 – 0.8 mm wide, with large 3-lobed stelidia of which 1 lobe forward recurved and 2 lobe erect, much exceeding in length anther cap; column foot 0.8 – 1.2 mm long, forward curved. Anther cap hemispheric, 0.5 – 0.6 mm across, beak short, broad, truncate, finely erose along the margin. Pollinia 4, narrowly ovoid, 0.4 mm long. Fruits unknown.

Etymology: —Species epithet refers to Bidoup Mountains where the largest population of this species was recently found.

Ecology: —Creeping epiphyte; primary broad-leaved, evergreen, humid montane forests. (600) 800 – 1,800 m a.s.l. Fl. May – June. Rare. Estimated IUCN Red List status—DD.

Distribution: — Vietnam: Dak Nong (Dak Glong district, Nam Nung nature reserve), Lam Dong (Dalat City area; Lac Duong district), Ninh Thuan (Ninh Son district). Endemic.

Additional specimens studied (paratypes): — VIETNAM: Ninh Thuan province, Ninh Son district, Phuoc Binh municipality, in 34 km to NE from Dalat city (12°07'N, 108°42'E), 4 April 1997, Averyanov, Binh, Loc VH 3598 ( LE!, HN) ; Lam Dong province, Lac Duong district, Da Chay municipality, 35 km to NE from Dalat city, W macroslope of Gia Rinh Ridge (12°09'N, 108°41'E), 4 May 1997, Averyanov, Binh, Hiep, Loc, Lowry VH 4554 ( LE!, HN) ; Lam Dong province, Dalat City area , April 2010, Averyanov s.n. (LE-photo!) ; Dak Nong province, Nam Nung nature reserve , 8 March 2013, Canh s.n. (LE-photos!) .

Notes: —This species is similar to members of sect. Brachystachyae on its overall morphology and plant habit, as well as in purple colouring of the flowers, a wing-like tooth on the upper margin of the stelidia and 4 pollinia ( Vermeulen et al. 2015). However, it has no close relation to species of this section presently recorded in Vietnam such as Bulbophyllum holttumii Hawkes (1956: 92) (= B. apiferum Carr (1930: 133)) , B. khasyanum Griffith (1851: 284) , B. repens Griffith (= B. poilanei Gagnepain (1930: 147)) and B. xylophyllum Reichenbach (1874: 151) . The described plant may be more or less closer to the east Himalayan B. cylindraceum Wallich ex Lindl. in Lindley (1840: 53) and B. nujiangense X.H.Jin & W.T.Jin in Jin et al. (2014: 157) (= B. anodon Vermeulen et al. (2014: 14) , B. cylindricoides W.H.Chen & Y.M.Shui in Shui & Chen (2006: 217)), from which it distinctly differs in having a miniature habit, small leaves, lax inflorescence, narrow acuminate 3-keeled sepals and large 3 lobed stelidia. It is remarkable that the long laxly inflorescence and narrow, acuminate sepals indicate a rather uncertain intermediate position of B. bidoupense between section Brachystachyae and sect. Stachysanthes ( Blume 1825: t.. 64) Averyanov (1994: 276) ( Vermeulen & O’Byrne 2008: 152). There are no closely related species in section Stachysanthes resembling this newly described plant. Compared to all species within both mentioned sections, B. bidoupense differs in having small, succulent, fleshy, sub-terete leaves, 3-keeled sepals and a large 3-lobed stelidia much exceeding the anther cap in length.

Bulbophyllum bidoupense is endemic to higher elevation areas spreading across the central part of southern Vietnam and known in Vietnamese geography as the Central Highlands or Tay Nguyen Plateau. Phytogeographically, the largest part of this area coincides with the South Annamese floristic province of the Indochinese floristic region that is particularly rich in plant diversity and endemism (Averyanov et al. 2003). The species is probably fairly common here in the forests of the highest mountain formations, particularly within the Bidoup, Gia Rinh and Hon Giao Ranges. This miniature plant typically grows within the canopies of tall trees and, thus, is difficult to observe directly. It has small unattractive flowers and is easily overlooked during botanical investigations and this explains why it is scarce in herbarium collections. As a result, the exact distribution of this species and its Red List status remain uncertain.

Figures

FIGURE 1. A. Habitat of Bulbophyllum bidoupense Aver. & N.V.Duy and Schoenorchis hangianae Aver. & N.V.Duy, primary broadleaved evergreen forest on slopes of Hon Giao Range in Bidoup Mountains. Bulbophyllum bidoupense. B, C. Flowering plants in nature habitat. D, E. Inflorescence of plants from different populations. F, G. Flowers, half-side and side views (B—type specimen, VTV 1030; C, E–G—specimen L.Averyanov s.n. April 2010; D—specimen Nguyen Van Canh s.n. 8 March 2013). Schoenorchis hangianae. H–K. Flowering and fruiting plants. L. Portion of inflorescence. M, N. Flowers (type specimen VTN 984). [Photos of Nong Van Duy, L. Averyanov and Nguyen Van Canh, correction and design by L. Averyanov].

FIGURE 2. Bulbophyllum bidoupense. A. flowering plants. B. Leaves and pseudobulbs. C. Portion of inflorescence. D. Flower, half-side view. E. Floral bracts. F. Flattened sepals and petals.G. Ovary, column and lip with removed sepals and petals, side view. H.Lip, side view, frontal view and view from behind. I. Ovary and column with removed tepals and lip. J. Column, frontal and half-side view. K.Anther cap, views from above, from below and half-side view. L. Pollinia. [All drawn from the type—VTN 1030 by L. Averyanov and T. Maisak].