Orchidantha yunnanensis P.Zou, C.F.Xiao & Škorničk., 2017

Zou, Pu, Xiao, Chun-Fen, Luo, Shi-Xiao, Cui, Chang-Jie, Xu, Kai, Ye, Yu-Shi, Liao, Jing-Ping & Leong-Škorničková, Jana, 2017, Orchidantha yunnanensis (Lowiaceae), a new species from China, and notes on the identity of Orchidantha laotica, Phytotaxa 302 (2), pp. 181-187 : 182-186

Orchidantha yunnanensis P.Zou, C.F.Xiao & Škorničk. , sp. nov. ( Figs. 1 , 2 ).

Type:— CHINA. Yunnan: Malipo County, Voucher from a cultivated plant at the Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, 20 March 2016, P. Zou, C. F. Xiao, C. J. Cui & K. Xu ZP54 (Holotype IBSC-0813229! including materials preserved in alcohol).

Diagnosis:—Similar to Orchidantha insularis T.L.Wu , but differs in the narrowly obovate dorsal sepal which is almost twice as broad as lateral sepals (compared to O. insularis with narrowly ovate dorsal sepal which is almost equal or only slightly broader than the lateral ones) and narrowly dark purple labellum with a pale yellow or white raised midrib (compared to ensiform labellum which is dark violet at base and yellow greenish at apical half).

Description: —Perennial, clump-forming herb, 50–150 cm tall. Rhizomes erect, ca. 1 cm in diameter, white internally. Petiole 19–57 cm, furrowed, sheathing in basal 1/3. Leaf blade narrowly elliptic, obviously unequal, 77–125 × 15–19.5 cm, green and glabrous on both sides, obtuse at base, acuminate at apex. Inflorescence on a slender, richly branched, pale-coloured, burrowing stem with prominent bracts or their scars.

Prophyll, second and third bracts cream to bright green, sometimes with sparse claret tinge towards apex, glabrous; prophyll triangular, 2-keeled, ca. 2 cm long, ca. 1.1 cm broad (at base); first bract ca. 3.3cm long, apex minutely mucronate, second bract ca. 5.2 cm long, apex minutely mucronate. Floral bract appearing above the soil or with the proximal part buried in the soil, deep claret, minutely mucronate, 5.6–6.7cm long, ca. 2–2.7 cm wide, sheathing the 2.2–2.9 cm long ovary extension and extending ca. 2.5 cm beyond it. Flowers open in the morning, are presented above the ground, and emit a strong unpleasant smell of a dead fish. All sepals glabrous, minutely mucronate, cream white to pale green at base to green adaxially, with a more or less rich claret tinge abaxially; lateral sepals overlapping and forming a boat-shaped structure supporting the labellum, narrowly oblong, 6.0– 6.6 cm long, ca. 1.2 cm wide; dorsal sepal arching over the petals and labellum, forming a claw-like structure, narrowly obovate, 5.7–6.3 cm long, 1.9–2.3 cm wide. Lateral petals overlapping at base covering stamens and style, dark purple, unequally oblong, apiculate, internal margin straight, exposed margins irregularly serrate at apex, straight towards the base, ca. 2 cm long, 0.3–0.4 cm wide. Labellum narrowly oblong, with slightly involute margins, 5.6–6.4 cm long, 1.2–1.6 cm at widest point, dark purple, with a pale yellow or white raised midrib (midrib ca. 0.4 cm wide, semi-circular in cross-section), sides of the labellum prominently tessellate, margin entire, irregularly undulate. Stamens five, 0.9–1.0 cm long, cream but richly tinged with claret at the base of filaments, glabrous; filaments ca. 0.2 cm long, anther thecae 0.7–0.8 cm long, longitudinally dehiscent throughout their length. Style 0.7–0.8 cm long, purple, glabrous; stigma 0.7–0.9 cm long, deeply three-lobed, finely fimbriate at margin, tinged with claret (except secreting tissue); median lobe ca. 0.8 cm, easily separated from the lateral lobes; lateral lobes 0.2–0.6 cm; secreting tissue (viscidium) placed ventrally, V-shaped, cream to pale yellow, and pronounced in side view. Ovary almost cylindric (slightly thicker than the rest of the ovary extension), ca. 0.5 cm in diameter, 3-1ocular, white to cream white, glabrous; each locule with 6–7 ovules attached to the axial side of the placenta in two rows. Ovary extension 2.2–2.9 cm long, cream-white with slight reddish tinge towards the sepals. Fruits and seeds not seen. Based on living material accession 20013005 (Xishuangbanna Tropical Botanic Garden) and a spirit material accession ZP54 (IBSC).

Etymology: — Orchidantha species are so far known to be quite restricted in their distribution range. We name this species after Yunnan province, where this species is native.

Phenology: — Orchidantha yunnanensis has been observed in flower at the Xishuangbanna Tropical Botanic Garden under cultivation from the end of March to the middle of April.

Additional specimen examined (paratype): — CHINA. Yunnan: Malipo County. Voucher from a cultivated plant at the Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, 22 March 2016, P. Zou, C. F. Xiao & K. Xu ZP55 (HITBC)

Chinese name: —ȓffi±AEṭ (yun nan lan hua jiao)

Relationships: —Within China, Orchidantha yunannensis can be readily recognized from both varieties of O. chinensis by its claw-shaped appearance of the flower caused by arrangement of lateral sepals overlapping basally and supporting the labellum while the dorsal sepal arches over. Orchidantha yunannensis is more similar to O. insularis in its claw-shaped appearance of the flower (which is, however, much more prominent in O. yunannensis ) and by the structure of its labellum with a prominently raised midrib (semi-circular in cross-section). As outlined in the diagnosis, it differs by its shape and colour (narrowly oblong, 5.6–6.4 × 1.2–1.6 cm, dark purple throughout with pale yellow to white midrib in O. yunannensis compared to ensiform 5.5–6.2 × 0.6–0.9 cm, dark violet at base gradually changing to yellowish-green at apex in O. insularis ) as well as by the way it is positioned in the flower (labellum is kept within the lateral sepals in O. yunannensis while it points above the lateral sepals in O. insularis ; for comparison, see Fig. 1B in Zou et al 2014).

Outside China, Orchidantha yunannensis is most similar to Orchidantha laotica but the main differences lie in the size of the flowers (more than twice as large in O. yunannensis than in O. laotica ) as well as the shape and structure of the labellum. Labellum in O. yunannensis is narrowly elliptic to narrowly obovate, 5.6–6.4 × 1.2–1.6 cm, dark maroon with prominently thickened yellow to pale yellow midrib (which is semi-circular in cross-section). The sides at the base of the labellum do not overlap over the petals. Orchidantha laotica has labellum ovate with sharply aristate apex, ca. 2.5 cm long and ca. 1.3 cm wide (near base at the widest point), dark purple with a series of bright yellow lamellae ( Fig. 2F ) and the basal side of the labellum overlaps and almost completely covers petals ( Fig. 2C ).

Figures

FIGURE 1. Orchidantha yunnanensis P.Zou, C.F.Xiao & Škorničk. A. Habit; B. Detail of flowers; C. Old inflorescences showing the dense branching (scale 10 cm); D. Detail of the part of the inflorescence (scale 5 cm); E. Dissection (from left): prophyll, first bract, second bract, floral bract, two lateral sepals, dorsal sepal, labellum, and the rest of the flower (peduncle, ovary and ovary extension with petals, anthers and stigma attached) (scale 5 cm); F. Detail of anthers and stigma (front and back views), two petals (back and front view), crossection and longitudinal section of ovary. All based on P. Zou, C. F. Xiao, C. J. Cui & K. Xu ZP54. (Photo by P. Zou)

FIGURE 2. Orchidantha yunnanensis P.Zou, C.F.Xiao & Škorničk. A. Habit; B. Flower (side view); C. Lateral petal (ventral and dorsal view); D. Stamens and style (ventral and dorsal view); E. Ovary (longitudinal section); F. Prophyl G. Second bract; H. Floral bract; I. Lateral sepal (ventral view); J. Lateral sepal (dorsal view); K. Dorsal sepal (dorsal view); L. Labellum; M. stem with pedicel and ovary extension (side view). Scales: B (5 cm); C–E (1 cm); F–M (5 cm).All from P. Zou, C. F. Xiao, C. J. Cui & K. Xu ZP54 (IBSC) and living material of XTBG 20013005. (Drawn by Ms. Yun-Xiao Liu)