Growth form Epiphyte, patent, at base sparsely branched, up to 40 cm high. Rhizome not seen. Roots filiform, flexible, glabrous. Stem usually curved, slightly compressed, rigid, proliferously leafed, completely covered by leaf sheaths. Leaf ligulate, erect-patent, glabrous, carnose; apex strongly unequal 2-lobed, both lobes obtuse; base cuneate; lamina 5-8.5 cm long, 0.7-0.9 cm wide; sheath tubular, tight, sparsely warty, dark brown, 1-1.5 cm long; apex toothed, with glabrous margin. Inflorescences terminal, capitulate, many-flowered, sub-globose, elongated, 3 cm long, 2 cm wide, when young enveloped by a spathe. Spathe broad, apex apiculate; floral bracts transparent, thin. Flowers upright, glabrous. Median sepal oblong, apex obtuse, 1 cm long, 0.4 cm wide. Lateral sepals oblique, fused up to the apical third, base shortly saccate-concave, 1.18 cm long, 0.36 cm wide. Petal oblique, ligulate-oblong, apex obtuse, glabrous, base narrowed, 1.12 cm long, 0.44 cm wide. Lip broadly elliptic, 0.3 cm long, 0.25 cm wide; epichile broadly obtuse; hypochile slightly narrowed, spurred; spur decurved, oblongoid, 0.4 cm long, 0.2 cm wide. Column 0.2 cm long, glabrous; clinandrium 5-lobulate; stelidia not seen. Anther broadly cucullate, with obtuse projection, in front retuse, glabrous, 0.3 cm long, 0.24 cm wide; pollinia not seen; stigma not seen; viscidium not seen. Ovary cylindric, glabrous, 0.6 cm long, subsessile. Capsule not seen.
Distribution – Papua New Guinea.
Habitat and Ecology - Epiphyte in montane forest. Altitude 1300 m. Flowering in January in the wild.
2. The epithet melanocaulon refers to the dark brown leaf-sheaths of the species.
3. Specimen observed: Schlechter 19058.