Habenaria Willd. including about 876 species, is one of the largest genera of terrestrial orchids, and mainly distributed in tropical and subtropical areas^[1]. According to Flora of China, 54 species (19 endemic) were reported in Habenaria^[2]. Further investigation, has found many new species and newly recorded species from China, such as H. anomaliflora, H. myriotricha, H. vidua, H. yachangensis and H. luquanensis^[3-7].

During the floristic survey in limestone areas of Guangxi, China, an unfamiliar species of Habenaria was found in karst forest in Longgang National Nature Reserve. It is mainly characterized by the leaves adpressed to ground, the flowers lilly-white, raceme lax, lip spurred and 3-lobed, with low rim around entrance to the spur, side lobes much smaller than median lobe. It is similar to H. delavayi in rosulate leaves which are adpressed to ground, but its lilly-white flowers are quite different from the latter. Our results of taxonomic study^[8] indicated that it represented an undescribed species of Habenaria in China——H. lindleyana Steud., which is reported below.

宽叶玉凤花    新拟    Fig. 1

Habenaria lindleyana Steud., Nomencl. Bot. (ed. 2) 1: 717. 1840; Seidenf., Opera Bot. 114: 61. 1992; Aver. Identif. Guide. Vietnam. Orch.: 66. 1994; Aver. et Averyanova. Updated Checklist Orch. Viet.: 38. 2003.——H. latifolia Lindl., Gen. Sp. Orchid. Pl. 321. 1835, non Kunth (1816). Type: Ceylon (Srilanka), Macrae s. n.

——H. columbae Ridl, Gard. Chron. 2: 390. 1900.

——H. macroptera Gagnep., Bull. Soc. Bot. France 78: 72. 1931.

Herbs, terrestrial, 30-40 cm tall, 3-6 rosulate leaves adpressed to ground, scape with 5-10 small adpressed bracts. Tubers elliptic, oblong or ovoid, 3-5 cm long, 2-2.5 cm wide. Leaf blade ovate to suborbiculate, obtuse, 5-10 cm long, 2-7 cm wide, slightly fleshy, base obtuse-rounded, apex obtuse or acute. Inflorescence racemose, 8-20 cm long, with 6-25 flowers. Floral bracts cuneate, acuminate, 1.5-2 cm long, ca. 4 mm wide, shorter than ovary. Flowers white; ovary fusiform, slightly arching, 2-2.5 cm long, 2-3 mm in diam., glabrous. Median sepal narrowly ovate, obtuse, 7-9 mm long, ca. 5 mm in diam.; lateral sepals ovate, slightly oblique, obtuse, spreading, 1-1.5 cm long, 6-8 mm in diam. Petals lanceolate, 7-8 mm long, ca. 2 mm wide. Lip spurred, 3-lobed, with low rim around entrance to the spur. Median lobe narrowly obovate, 1-1.6 cm long, ca. 0.6 cm wide, rounded at apex; side lobes narrowly lanceolate, much smaller, 2-5 mm long, ca. 1 mm wide, apex acute. Spur filiform, 3-3.5 cm long. Anther 3.5-4 mm tall; thecae broadly divergent toward base; viscidium bent upwards, 4-5 mm long; stigmas straight, narrow, acute.

Distribution: Vietnam (Dong Nai), Thailand, Laos, China (Longzhou County, Longgang National Nature Reserve of Guangxi).

Habitat: Habenaria lindleyana grows on karst limestone hillside with 40°-50° W or SW slope, at an elevation of 200-300 m. The tree layer is up to 10 m tall, with a canopy cover of 65%, including Sterculia monosperma, Cleistanthus sumatranus, Delavaya toxocarpa and Radermachera sinica. The shrub layer cover is 80%, including Diospyros eriantha, D. saxatilis, Miliusa chunii, Uvaria tonkinensis and Desmos chinensis. The herb layer cover is 90%, consisting of Microstegium fasciculatum, Bidens pilosa, Selaginella delicatula, S. uncinata, Asplenium sampsonii. At present, the population is mainly distributed in periphery of Longgang National Nature Reserve, the only one locality known in China. Besides, it is very easily affected by the local residents, through forest clearance for cultivation, tree-cutting, digging and grazing, etc.

Additional specimens examined: China. Guangxi: Chongzuo City, Longzhou County, Longgang National Nature Reserve, grows in karst forest, hillside, 300 m, 17 Sep. 2015, Yu-Song Huang and Wei-Bin Xu Y3137 (IBK); the same location, grows in periphery of forest, foot of limestone hill, 250 m, 18 Sep. 2015, Wei-Bin Xu and Yu-Song Huang 12414 (IBK).

Conservation status: H. lindleyana is a rare species, and only one population (fewer than 100 individuals) is known in China. More native populations of H. lindleyana could be discovered from other limestone areas of Longgang National Nature Reserve, or in the Sino-Vietnamese border area. We therefore consider H. lindleyana to be Data Deficient (DD)^[9].

Acknowledgments: We thank the staffs of Longgang National Nature Reserve for the help and support. We also thank Prof. Yan Liu (IBK) for his comments on the manuscript and providing relevant references.