Rhizome 2-3.5 mm in diam., sections between pseudobulbs 0.6-2.5 cm. Pseudobulbs close, ovoid or broadly conic, 0.8-1.7 × 1-2 cm.

Petiole 0.8-2 cm; leaf blade elliptic to ovate, 6-13 × 0.9-1.7 cm, obtuse.

Inflorescence an elongate, rather lax raceme, erect to spreading, 23-44 cm, 13-27-flowered; peduncle 8-22 cm; bracts ca. 5, longest 6.5-9 mm; rachis not thickened, 9-20 cm, glabrous; floral bracts triangular, 1.8-4.5 × 1-2 mm, acuminate. Flowers spreading to reflexed, secund, not fully opening, many simultaneously, yellowish, stained with blackish purple and with blackish purple veins, sometimes entirely blackish purple adaxially and pale reddish brown abaxially, petals and lip almost entirely blackish purple, petals proximally sometimes yellow with a blackish purple vein. Pedicel and ovary 5-11 mm. Dorsal sepal porrect to recurved, ovate to triangular, 5.5-9.5 × 1.8-3.2 mm, rather thin, adaxially pubescent, abaxially glabrous, base rather narrowly attached, margin ciliate, apex obtuse to acute; lateral sepals recurved, 6.5-10.5 × 2.7-4.2 mm, otherwise as dorsal sepal. Petals ± porrect, elliptic to obovate or spatulate, 1.5-2.5 × 0.8-1.5 mm, rather thin with a thick top, surface pubescent distally, base broadly attached, margins ciliate distally, apex obtuse to acuminate; lip recurved in proximal half, obovate to elliptic, 5-7 × 2-3.3 mm, rather thin; abaxially with a wide, rounded ridge near base, surface elsewhere concave to flat, glabrous or partly pubescent; adaxially somewhat concave near base and with a median slit or furrow reaching up to 1/3-2/3 of lip, with 2 distinct, obtuse ridges diverging proximally, continuing over 1/3-3/4 of lip, and often ending in a patch of irregularly shaped verrucae, surface glabrous, margin ciliate, apex rounded to obtuse. Column 1.4-1.8 mm; stelidia triangular, 0.5-0.8 mm, acute. Fl. Jan-May, Jul.