Bulbophyllum cavibulbum J.J.Sm., Nova Guinea 14 (1929) 465, pl. 76, fig. 112
Type: Lam 1689 (holo BO); para
Rhizome erect to patent, up to 30 cm long, 1.8-3 mm diam. Roots present only below the pseudobulbs, along the older parts of the rhizome. Pseudobulbs ovoid, 1-3.5 cm apart, 0.6-1 by 0.4-0.6 cm, not flattened. Petiole 0.5-1.5 mm. Leaf blade ovate to elliptic, 1.2-3.2 by 0.6-1 cm, index 2-4.5, tip acute. Inflorescences usually many together on a short sympodium, approx. 2 cm, 2-flowered. Peduncle c. 0.4 cm; bracts c. 3, the longest 3-4 mm. Rachis approx. erect, c. 0.3 cm. Floral bracts ovate, 6-8 mm, tip acute. Pedicel and ovary 4-5 mm, with the node c. 1 mm from the floral bract. Flowers distichous, scattered, both open at the time, moderately opening. Median sepal ovate, 1521 by 0.3-0.4 mm, index 5-6, tip long acuminate to caudate; margins somewhat papillose; rather thin; surface glabrous. Lateral sepals oblique, otherwise as the median sepal. Petals hardly oblique, ovate to elliptic, 4.2-5.5 by 2.2-3 mm, index c. 2, tip acute; rather thin; glabrous. Lip curved, general outline ovate, 3.8-4.5 by 1.5-2 mm, index 2-2.5 (not spread), tip subacute; rather thick; approx. glabrous; adx. moderately concave and with 2 inconspicuous knobs near the base, with 2 inconspicuous ridges converging in front, abx. with a distinct, retuse median ridge. Column from ovary to the tip of the stelidia c. 1.5 mm; stigma not protruding at its base, slit-like. Stelidia inconspicuous, triangular, tip subacute; upper margin somewhat irregular. Anther abx. with a ridge towards its base; front margin protruding. Pollinia 4; the inner pair approx. half as long as the outer pair.
(After Vermeulen, 1993)