Bulbophyllum atrorubens Schltr., Bot. Jahrb. Syst. 39 (1906) 82
Type: Schlechter 15495 (holo B, lost; iso K, P)
Clustered, small epiphyte. Rhizome creeping, 1.2-1.5 mm diam., sections between pseudobulbs 0.2-0.7 cm long, bract fibres persistent. Pseudobulbs minute, ovoid, 0.4-0.9 by 0.5-0.6 cm, not angular. Leaf with petiole 1.6-3 cm long; blade elliptic-obovate, 3.5-6 by 1.9-2.5 cm, index 1.8-3; rounded. Inflorescence a very dense, globose or shortly ellipsoid-cylindrical raceme, 12.5-17 cm long, 12-22-flowered. Peduncle 11.8-16 cm long, bracts 3. Rachis arching or nodding, 0.7-0.9 cm long. Floral bracts c. 1 mm long, acute. Flowers: Pedicel and ovary c. 2 mm long. Median sepal somewhat recurved, triangular, c. 2.2 by 2.8 mm, index c. 0.8, top obtuse, not cucullate, margins entire, surface glabrous. Lateral sepals free, as the median but oblique, ovate, c. 2.8 by 2 mm, index c. 1.4. Petals somewhat recurved, obovate, c. 1.7 by 1.2 mm, index c. 1.4; rounded, margins slightly erose, surface glabrous. Lip distinctly curved, broadly spathulate; c. 1.5 by 1.6 mm, index c. 0.9; rounded, margins finely papillose towards the top; adaxially deeply concave near the base, with 2 distinct, high, finely papillose ridges starting near the base, close to the margin, then lower and converging slowly but leaving a deep, almost glabrous furrow in between, ending at about of the length of the lip, top part of lip convex, area between ridges and margins densely and coarsely papillose; abaxially with a truncate ridge near the base, flat towards the tip, surface glabrous. Column c. 0.8 mm long, foot without teeth. Stelidia straight, c. 0.9 mm long, triangular, acute, with a large, triangular, obtuse tooth along the upper and lower margin. (After Vermeulen, ms.)
Colours: Flowers entirely reddish purple.
Habitat: Epiphyte in lowland forest.
Distribution: Malesia (New Guinea), New Caledonia.
Distribution in New Guinea: Papua New Guinea; see map 96-151M.jpg.
Cultivation: Warm growing epiphyte.