Tên Khoa học: Cleisostoma phitamii Tich et Aver.Tên tiếng Anh: Tên tiếng Việt: Mật khẩu phi tâmTên khác:
Perennial monopodial epiphytic herb. Stems simple or few branched, slender, pendent, 15-50 cm long, 2.5-3 mm in diam.; internodes 0.8-2.2 cm long. Leaves, succulent, terete, 5-9 cm long, 2-3 mm in diam., obtuse, straight to slightly curved. Inflorescence short lateral raceme 2.5-3.5 cm long, 3-5 flowered, scape and rachis greenish-brown; floral bracts triangular, acute, about 1.3 mm long, 2.5 mm wide. Flowers widely opening, about 1.5 cm across; sepals and petals rigid, dull pale yellowish-green with irregular dark purple-brown spots; lip white with light purple-pink at the center of median lobe and at base of spur, yellowish along edges of side lobes; column white, pink at back. Pedicel and ovary greenish-purple, 7-10 mm long and 1 mm in diam. Dorsal sepal narrowly obovate, concave, cucullate, obtuse, 10-11 mm long, 3-5 mm wide near the apex. Lateral sepals spreading, narrowly obovate, oblique, obtuse, 9-10 mm long, 4-5.5 mm wide. Petals obliquely lanceolate spatulate, 9 mm long, 2.5-4 mm
2.5- wide near the apex. Lip spurred, 9 mm long (from the base to the apex of median lobe), 6 mm wide (when flattened); side lobes erect, 2-3.5 mm tall, 4-5 mm long, with incurved yellowish fleshy edges fused at front together into erect wall 3 mm broad and 2 mm tall, spreading into spur entrance in form of fleshy hairy longitudinal protuberance; median lobe transversely rhomboid, fleshy and inflated at the center, indistinctly 3-lobulate, 4-5 mm long, 7-8 mm wide, lateral lobules thin, obtuse, median lobule fleshy, triangular. Spur broadly conical, more or less straight, 2-3 mm long, 1.5 mm diam., shallowly bilobed at apex, inside hairy near entrance, in apical half with longitudinal septum. Back-wall callus rhomboid, erect, straight, fleshy, raising from base of lip and back-wall of spur, 3.5-4 mm long, 2 mm wide, truncate bilobulate at apex; adaxially flat, in the center with small retrorse thin lamella; abaxially with 2 longitudinal bosses hairy at base. Column stout, erect, broad, slightly forward curved, 8.5-9 mm high, 2.5 mm wide. Anther cap hemispherical, 2 mm in diam., shortly beaked. Stipe (tegula) 3 mm long, suddenly broadening into large spatulate truncate subquadrate viscidium 2 mm long and wide. Pollinia 2, each half-split into 2 subequal hemispheric portions. Fruits unknown.
Etymology: Species name refers to the name of its discoverer and orchid enthusiast - Mr. Nguyen Phi Tam.
Ecology: Epiphyte. Evergreen broad-leaved closed submontane forests. 600-800 m. Fl. August - October. Very rare. Estimated IUCN Red List status - CR [A1ac; B1+2ab(i-iv); C1; D1+2].
Distribution: Vietnam: Khanh Hoa (Khanh Son), Lam Dong (Prenn). Endemic.
Studied specimens (paratypes): VIETNAM: Khanh Hoa province, Khanh Son district, Son Trung municipality, Mt. O Kha (Suoi Che), 19 July 2013, Nguyen Thien Tich, specimens no Tich 19-07-13 (SGN); Lam Dong province, Dalat City, fresh wild collected plant found on local orchid market, 9 September 2013, Nguyen Phi Tam, Nguyen Thien Tich, specimens no Tich 09-09-13 (SGN, LE - photo); Lam Dong province, Dalat City, Prenn area, October 2014, Nguyen Thien Tich, specimens no Tich 00.10.14 (SGN, LE, LE - photo).
Note: Flowers of this species superficially resemble flowers observed in the genus Gastrochilus D.Don which it is not closely related to. At the same time the unusual lip structure with a goblet-shaped epichile bordered at the front by a high wall, as well as the broad rectangular pollinarium stipe supports the very isolated position of this plant in the genus. The plant obviously does not fit with established generic sections proposed by Seidenfaden (1975) and, due to its unique floral structure supports the segregation of it into a separate monotypic section.