Bulbophyllum trachypus Schltr., Repert. Spec. Nov. Regni Veg. Beih. 1 (1913) 878
Type: Schlechter 18573 (holo B, lost; iso K)
Rhizome creeping, 1-1.5 mm diam. Roots spreading. Pseudobulbs discoid to ovoid, 0.5-2 cm apart, 0.25-0.4 by 0.2-0.3 cm, not laterally flattened. Petiole 4-8 mm. Leaf blade elliptic to slightly obovate, 3-4.5 by 1-2 cm, index 1.6-4.5, tip obtuse. Inflorescence usually single, 18-25 cm, up to 30-flowered. Peduncle 14-16 cm, coarsely verrucose; bracts 4, the longest 3-4.5 mm. Rachis erect, at most slightly zigzag bent, up to c. 9 cm, surface as peduncle. Floral bracts triangular, 4-5 mm, tip acute to acuminate. Pedicel and ovary c. 14 mm, with the node 4-5 mm from the floral bract. Flowers scattered, few open at the time, moderately opening. Median sepal elliptic, c. 6 by 6 mm, index c. 1, top emarginate with a straight to recurved, subulate projection c. 1.5 mm long, ending in a globular knob; margins glabrous to papillose; thin; surface glabrous. Lateral sepals connate over most of their length, oblique, c. 5.5 by 4 mm, index c. 1.3, tip an incurved, subulate projection c. 2 mm long; margins finely papillose; otherwise as the median sepal. Petals elliptic, c. 3 by 1.5 mm, index c. 2, tip rounded to acute-acuminate; margins glabrous to finely erose; thin; surface glabrous. Lip 3-lobed, median lobe distinctly curved, general outline elliptic, c. 1.5 by 0.7 mm, index c. 2 (not spread), tip obtuse; approx. entirely finely papillose; thick; adx. concave and with 3 parallel ridges near the base, which in front abruptly end into a triangular concavity bordered by 2 more ridges which in front converge; abx. with a distinct, retuse median ridge; basal lobes with the frontal margin inserted along the margin of the lip; large, semi-elliptic, tip rounded; front margin distinctly ciliate; thin; surface glabrous, papillose towards the margins. Column from ovary to the tip of the rostellum c. 1.5 mm; stigma protruding at its base, obovate; column-foot with inconspicuous, obtuse lateral wings close to the attachment of the lip. Stelidia approx. absent, lower margins of the column with a distinct, straight, subulate, acute tooth of c. 1.3 mm long. Anther abx. with a ridge towards its base; front margin protruding. (After Vermeulen, 1993)
Colours: Flowers pale yellow to yellowish green, sometimes tinged pink; or flowers dark purple.
Habitat: Epiphyte in lower montane forest; 1300-2100 m.
Flowering time in the wild: April, August, November.
Distribution: Malesia (New Guinea).
Distribution in New Guinea: Papua New Guinea; see map 96-1861M.jpg.
Cultivation: Intermediate growing epiphyte.