Pteroceras Hassk comprises about 19 species and is widely distributed from northwestern Himalaya to the Philippines^[1-2]. Before this study, five species of this genus have been recorded in China, and four from Yunnan^[3-5]. During our recent survey in Yunnan Province, a pretty species of Pteroceras was discovered. After extensive morphological comparisons^[6-8], it was identified as Pteroceras teres (Blume) Holttum, a new record to the Chinese orchid flora.

Pteroceras teres (Blume) Holttum in Kew Bull. 14: 271. 1960.——Dendrocolla teres Blume, Bijdr.: 289. 1825. Type: Java: Buitenzorg, Blume 744 (lecto-type L). (筒距长足兰Fig. 1)

(Fig. 1)

Fig. 1 Pteroceras teres (Blume) Holttum. A: Plants with blossom buds; B: Inflorescences; C: Leaf apex; D: Flower; E: Dorsal sepal, petal and lateral sepal; F: Anther cap; G: Pollinaria; H: Column (front view); I: Column and lip (lateral view); J: Lip (ventral view). Bars: E=3 mm; F, G=0.5 mm; H, I, J=5 mm

Monopodial epiphytes. Stems 10-20 cm long, bearing 5 to 12 leaves placed 1 cm apart. Leaves oblong-lanceolate, sessile, 6-13 cm long, 1.8-3 cm in diam., apex unequally bilobed, lobes obtuse to rounded. Inflorescences racemose, single or 2-4 superposed, emerging horizontal but becoming pendulous as they lengthen; peduncle 2-4 cm long, rachis terete, glabrous, bearing 3-10 flowers open at one time near the apex, lasting for only one day. Floral bracts scale-like, broadly triangular, greenish-white. Flowers spirally alternating, 14 mm in diam., sweetly scented; sepals and petals yellow or brownish yellow with fine or coarse reddish-brown spots on the adaxial side. Dorsal sepals obovate to elliptic, ca. 7 mm× 3.5 mm, obtuse at apex; lateral sepals spreading, obliquely obovate, ca. 8 mm×3.5 mm, truncate to rounded at apex. Petals narrowly obovate, ca. 7 mm× 2.7 mm, obtuse at apex. Lip 3-lobed and spurred, pointing forwards, ca. 7 mm long; lateral lobes oblong, erect and obtuse; mid-lobe very small, surface slightly papillose, with a ridge like callus. Spur irregularly cylindric or tubular, inflated at middle, gradually narrowing towards the apex, apex bladdery, laterally compressed, more or less recurved, usually dark reddish brown or purple. Column ca. 2 mm long, reddish brown; column foot 1.5-2.5 mm long, yellowish with reddish stripes; surface finely rugose-papillose. Rostellum much shorter; anther cap depressed, 0.5 mm wide, 2 celled; pollinia 2, waxy, subspherical, deeply longitudinal cleft, attached by a rhomboid-oblong stipe to a broadly obovate-triangular viscidium.

Distribution: India, Nepal, Bhutan, Thailand, Myanmar, Cambodia, Laos, Vietnam, Java, Sumatra, Borneo, Sulawesi and the Philippines. New record for China.

China: Yunnan, epiphyte on tree trunks in open forests or at forest margins in secondary forest, alt. 900-1150 m. L. Li 155 (IBSC).

Conservation status: This species is restricted in this region and confined to a small forest patch at present. It is considered to be vulnerable to extinction as 'Critically Endangered' (CR), according to IUCN red list categories and criteria^[9].

It is closely related to P. compressum (Blume) Holttum^[6-8], a species also recorded from Yunnan^[5], but the latter is characterized by having a laterally compressed rachis; white or cream flowers in two rows; spur with straight, rounded, often somewhat prolonged apex.