Bulbophyllum calviventer J.J.Verm., Orchid Monogr. 7 (1993) 156, fig. 109
Type: Sands et al. 1816 (holo K)
Rhizome when young creeping (but flowering already), later patent or pendulous, to 40 by 1.5 0.25 cm diam. Pseudobulbs approximately cylindrical, 0.3-0.7 cm apart, 1.23 by 0.3-0.4 cm, not flattened. Petiole 4-7 mm. Leaf blade elliptic to ovate, 3.8-7 by 0.5-1.3 cm, index 4.6-12; tip acute. Inflorescence 7-17 cm, 1-flowered; peduncle 5-14 cm. Floral bracts c. 4. the longest 0.3-0.5 cm. Floral bracts tubular, 2.5-5 mm; tip acuminate. Pedicel and ovary 8-15 mm, with the node 0.2-0.4 cm from the floral bract. Flowers moderately opening. Median.sepal ovate, 14-40 by 3-5 mm, index 4.6-10.5; tip long acuminate to caudate, margins finely papillose, thin; surface glabrous. Lateral.sepals free, oblique, 15-38 by 3.5-4 mm, index 5.8-9.5. margins approximately glabrous; otherwise as the median sepal. Petals triangular, deltoid or hastate, 1-2 by 1-1.2 mm, index 1-1.6; tip acute, margins glabrous to erose, thin; surface glabrous. Lip (slightly) curved base, sometimes slightly incurved tip, general outline ovate to triangular, 5.8-7 by 2.32.5 mm, index 1.9-2.8 (not spread); tip obtuse to acute, margins glabrous, thick; adaxially with a distinct basal concavety, basal teeth converging, together forming a transversely ridge with a deep notch half-way, basal part of the lip protruding distinctly beyond the ligament, distinctly concave (margins approximately spreading and somewhat curved upwards, fleshy), gradually passing into the convex top part of the lip; surface glabrous, but often slightly papillose towards the base; abaxially with an inconspicuously, truncate median ridge; surface distinctly papillose-pubescent. Column from ovary to the tip of the rostellum c. 1.8 mm; rostellum distinctly protruding; stigma slit-like, not protruding at its base. Column-foot with a distinct but very low, distinctly upwards pointing, rounded central knob above the attachment of the lip. Anther abaxially with a broad ridge; front margin hardly protruding. (After Vermeulen, 1993)
Colours: Median sepal white or cream-coloured, purple towards the tip, and locally suffused with purple, or with purple veins. Lateral sepals white, cream-coloured or pinkish base, purple elsewhere. Petals white or pale purple with a cream-coloured tip. Lip yellow, suffused with purple, or entirely purple. Column cream-coloured.
Habitat: Epiphyte in montane forest; 2100-2500 m.
Flowering time in the wild: September, December.
Distribution: Malesia (New Guinea).
Distribution in New Guinea: Papua New Guinea; see map 96-274M.jpg.
Cultivation: Cool growing epiphyte.