Bulbophyllum chthonochroma J.J.Verm. & Sieber, Malesian Orchid J. 15 (2015) 39.
Type: Hort. Vienna O-00B 823-1 (holo WU).
Small, short-creeping epiphyte with spreading roots. Rhizome creeping, 0.2-0.25 cm diam.; rhizome scales not persistent. Pseudobulbs 0.5-0.9 cm apart, not angular, ellipsoid-cylindrical to ovoid-cylindrical, 0.9-1.3 x 0.4--0.8 cm. Leaf elliptic, index 1.6-2.1; petiole 0.2--0.4 cm long; blade 1.7-3.8 by 0.9-1.8 cm, with rounded apex. Inflorescence c. 1.8 cm long, 1-flowered; peduncle c. 0.4 cm long, scales c. 3. Floral bract c. 0.35 cm long. Pedicel and ovary c. 0.8 cm long; basal node c. 0.2 cm above the floral bract attachment. Median sepal c. porrect, ovate, glabrous, c. 0.6 by 0.3 cm, index c. 2.0 (not spread); margins entire; apical part folded along the midnerve and abaxially distinctly keeled; apex obtuse, incurved; 3-nerved. Lateral sepals flat, not keeled, glabrous; at the base recurved and falcate, c. 1.1 by 0.3.5 mm, index 3.1-3.2. Petals porrect, oblong, glabrous, c. 0.23 by 0.09 cm, index 2.5-2.6; margins entire; apex with 3 teeth, the median tooth acute, the lateral ones shorter, truncate; 1-nerved near the base, with 2 branches from near the base. Lip recurved c. halfway, c.. ovate, c. 0.19 by 0.09 cm, index c. 2.1 (not spread); margins minutely hirsute, surface glabrous; adaxially slightly concave near the base, slightly convex towards the apex; abaxially with a distinct ridge with an approx. flat crest over most of its length; apex obtuse. Column including stelidia c. 0.18 cm long; rostellum not protruding, stigma inverted triangular; column foot at the apex not widened; stelidia porrect, deltoid, c. 0.04 cm long; apex acute, with close to the apex a minute, deltoid, subacute tooth along the upper margin; pollinia 2.
(after Vermeulen & Sieder 2015)