Bulbophyllum concavibasalis P.Royen, Alp. Fl. New Guinea 2 (1979) 167, fig. 64
Type: Brass 9531 (holo L (not found); iso AMES, BO)
Rhizome creeping, 1.6-2 mm diam. Pseudobulbs ovoid, 0.2-0.8 cm apart, 0.7-2 by 0.7-0.8 cm, hardly flattened. Petiole 8-18 mm. Leaf blade elliptic, 3-4.$ by 0.9-1.3 cm, index 2.8-4.2; tip obtuse. Inflorescence 11-15 cm, 1-flowered; peduncle 5.5-8.5 cm. Floral bracts c. 3. the longest 0.6 cm. Floral bracts tubular, 4-4.5 mm; tip acuminate. Pedicel and ovary 40-56 mm, with the node 0.4-0.5 cm from the floral bract. Flowers moderately opening. Median sepal ovate, 28-34 by 5-6 mm, index 4.6-6.8; tip sharply acute, margins finely papillose-erose, thin; surface glabrous. Lateral sepals free, 28-29 by 6-6.5 mm, index 4.3-4.8; otherwise as the median sepal. Petals oblique, ovate to orbicular, 4-5 by 4-4.5 mm, index 1-1.2; tip rounded to obtuse, margins cruse or papillose; very thin; surface glabrous. Lip approximately straight, general outline approximately strap-shaped with a wider base, 16-21 by 0.3-0.4 cm, index 5.2-5.3 (nor spread); tip obtuse to acute, margins finely irregularly ciliate, rather thin; surface approximately glabrous; adaxially with a rather distinct basal concavety, basal teeth converging, together forming a transversely ridge, part of the lip concave, gradually passing into the flat top part of the lip; abaxially approximately without a median ridge. Column from ovary to the tip of the rostellum c. 2.2 mm; rostellum distinctly protruding; stigma approximately orbicular, protruding at its base. Column-foot with a distinct, approximately straight, rounded central knob above the attachment of the lip. Anther abaxially with a ridge; front margin somewhat protruding. (After Vermeulen, 1993, as B. loroglossum)
Colours: Sepals greenish or light yellow, with or without small purple dots. Lip cream-coloured to bright yellow.
Habitat: Epiphyte in montane forest; 3000-3100 m.
Flowering time in the wild: August.
Distribution: Malesia (New Guinea).
Distribution in New Guinea: Papua New Guinea; see map 96-383M.jpg.
Cultivation: Cool growing epiphyte.