Danxiaorchis yangii B. Y. Yang et Bo Li, 2017

Yang, Boyun, Xiao, Shihe, Jiang, Yawen, Luo, Huolin, Xiong, Dongjin, Zhai, Junwen & Li, Bo, 2017, Danxiaorchis yangii sp. nov. (Orchidaceae: Epidendroideae), the second species of Danxiaorchis, Phytotaxa 306 (4), pp. 287-295 : 290-293

Danxiaorchis yangii B. Y. Yang et Bo Li , sp. nov. ( Figs. 2 A − I , 3 )

Diagnosis:— Danxiaorchis yangii obviously differs from D. singchiana in its Y-shaped callus adaxially bearing a remarkable obovoid appendage, and in its four pollinia narrowly elliptic in shape and equal in size.

Type:— CHINA. Jiangxi Province, Ji’an City, Jinggangshan Mountain , Jinggangshan National Nature Reserve , forest margins, under mixed shrubs, 26°27 ′ 06 ″ N, 114°30 ′ 43 ″ E, ca. 360 m a.s.l., 7 April 2016, B. Y.Yang 075 (Holotype: IBSC!; Isotypes: JXU!, JXAU!) .

Description:— Plant erect, 10–25 cm tall, holomycotrophic. Rhizome tuberous, fleshy, cylindrical, 5–15 mm long, 3–11 mm thick, with many minute and short branches, without roots. Scape terete, pale red-brown, slightly tinged with green-yellow, 2- to 3-sheathed; sheaths cylindrical, clasping stem, membranous, 25–45 × 4–7 mm. Inflorescence racemose, 4–8 cm long, 5- to 30-flowered; floral bracts oblong-lanceolate, 12–19 × 2.5–3.0 mm, apex acuminate, with sparse to dense purple-red spots; pedicel and ovary bright yellow, 15–25 mm long, glabrous; sepals yellow, obovateelliptic, dorsal sepals 11–16 × 3.5–5.5 mm, acute to obtuse; lateral sepals 12–18 × 3.6–6.3 mm, acute; petals yellow, narrowly elliptic, 8.0–15 × 3.5–6.0 mm, acute; labellum 3-lobed, with 3–4 pairs of purple-red stripes on side lobes and purple-red spots on middle lobe; side lobes erect, slightly clasping the column, subsquare, 3.5–4.0 × 5.0– 5.5 mm; mid-lobe oblong, 5.0–5.5 × 4.5–5 mm, apex acute to obtuse; labellum with two sacs at the base and a Y-shaped fleshy callus centrally; callus 4.0– 4.5 mm tall, extending from the base of disc to the base of mid-lobe, adaxially covering an additional obovoid appendage, ca. 3.0– 3.5 mm in diameter; column cream colored, straight, semi-cylindrical, 5.0– 5.5 mm long, footless; stigma concave, triangular, terminal; anther cap ellipsoid, ca. 1.3 mm in diameter; pollinia four, in two pairs, narrowly elliptic, granular-farinaceous, composed of friable massulae, each pair containing two pollinia equal in size with a thick caudicle attached to a common subsquare viscidium. Capsule purple red, fusiform, 35–45 mm long, 13–15 mm thick. Seeds dark brown, cylindrical, 1.7 × 0.8 mm, fleshy.

Etymology:— The specific epithet refers to the family name of the first author, Pro. Boyun Yang, who devotes himself to the conservation of orchids biodiversity in Jiangxi Province, China.

Distribution and habitat:— To date, the species was discovered only from Jinggangshan National Nature Reserve in western Jiangxi, eastern of China. It occurs in nearly the same longitude as D. singchiana but in higher latitude ( Fig. 4 ). D. yangii frequently grows at the margin of subtropical evergreen broad-leaved forest, under mixed shrubs and bamboo forest, in wet places at elevations of 360 m a.s.l.

Phenology:— Flowering was observed from mid April to mid May, and fruiting from mid May to late May.

Conservation status:— The species is currently known only from one site, and the observed total population is calculated as less than 250 individuals, so it should be considered an very small or restricted population and given an IUCN (2014) provisional conservation status of Endangered (EN, criterion D).

Additional specimens examined (paratypes):— CHINA. Jiangxi Province, Ji’an City, Jinggangshan Mountain, Jinggangshan National Nature Reserve, forest margins, under mixed shrubs, 26°27 ′ 06 ″ N, 114°30 ′ 43 ″ E, ca. 360 m a.s.l., 10 May 2016, B.Y.Yang 076 (JXU!).

Figures

FIGURE 2. Danxiaorchis yangii B. Y. Yang et Bo Li, sp. nov. A. Flowering plant and rhizome; B. Flower, front view (left) and bottom view (right); C. Dissection of a flower, showing dorsal sepal, petal, lateral sepal and labellum with column; D.Appendage of the labellum, side view; E. Column, side view (left) and front view (right); F.Anther cap, ventral view (left) and dorsal view (right); G. Pollinarium; H. Capsule.

FIGURE 3. Morphology of Danxiaorchis yangii B. Y. Yang et Bo Li, sp. nov. (A–I) and D. singchiana (a–c). A. Flowering in nature habitat and rhizome (showed in the black circle); B, a. Front view of a flower; C. Bottom view of labellum, showing two sacs; D. Front view of the Y-shaped appendage of labellum; E. Upper view of a labellum with column; F. Side view of a labellum with column; G, b. Side view of the Y-shaped appendage of the labellum; H. Capsule; I, c. Pollinarium. Scale bars: B, a = 1 cm; C, D, E = 5 mm; F, G, I, c = 1 mm; H = 1 cm; b = 2 mm. Images b and c were cited from the Figure 1 in Zhai et al. (2013).

FIGURE 4. Distribution map of Danxiaorchis yangii (circle) and D. singchiana (star).