Bulbophyllum sinapis J.J.Verm. & P.O'Byrne, Gard. Bull. Singapore 55 (2003) 156, fig. 15
Type: Jongejan cult. 171 (holo L), from Papua New Guinea, locality unknown
Rhizome 3-6 mm diam., sections between pseudobulbs 3-21 cm long, bract fibres thick, persistent. Pseudobulbs ovoid, 1-2.2 by 0.7-1.3 cm. Petiole 2-4.5 cm. Leaf blade elliptic to obovate, 8.5-19 by 2.4-7.5 cm, index (length/width) 2.4-5; rounded to obtuse. Flowers moderately opening. Median sepal spreading with incurved top part, obovate, 12-28 by 4.5-12 mm, index 2.1-4.2; acute to acuminate, base rather narrowly attached. Lateral sepals free, recurved but converging and (almost) touching towards the tip, triangular, with or without a small tooth along the lower margin, 10.5-22 by 7-13 mm, index 1.3-1.8; acuminate, base widely attached; otherwise as the median sepal. Petals recurved to spreading, obovate to elliptic, 11-30 by 3.8-8 mm, index 2.7-5; acute to acuminate, base narrowly attached. Lip recurved slightly below half-way the length of the lip, triangular with a drawn-out, narrowly linguiform top part , 5-10 by 5-8.5 mm, index 0.8-1.2 (all without artificial spreading); obtuse, margins with an acute angle above the base when the lip is observed in lateral view; thick; adaxially slightly concave near the base, convex towards the tip; abaxially with a retuse ridge nearly up to the top of the lip, top part concave. Column 3.4-6 mm long, c. straight in profile, stigma without teeth at the base; column foot without ridges. Stelidia porrect, triangular, 0.7-1.5 mm long, rounded to obtuse, lower margin without wing (a widely rounded wing may seem to be present in laterally flattened herbarium specimens). (After Vermeulen, ms.)
Colours: Sepals (mustard) yellow, the laterals with or without greenish tips. Petals somewhat more translucent (creamy) yellow. Lip (creamy) yellow. Flowers strongly and sweetly scented.
Flowering time in the wild: August, October.
Distribution: Malesia (New Guinea).
Distribution in New Guinea: Papua New Guinea; Papua New Guinea; see map 96-2220M.jpg.