Bulbophyllum section Hyalosema Schltr., Repert. Spec. Nov. Regni Veg. 10 (1911) 92
Small or medium-sized epiphytes. Rhizomes creeping; rhizome bracts thin, approx. glabrous, caducous including the veins. Roots sprouting below the pseudobulbs, spreading, glabrous to rugose, locally slightly hirsute. Pseudobulbs conspicuous compared to the size of the plant, 1-leafed, with shoots usually sprouting from its basal node and free, not fused to the pseudobulb. Leaves persistent, thick, veins inconspicuous. Inflorescences sprouting from nodes along the length of the rhizome, single; 1-flowered. Peduncle longer than the pseudobulbs, or with the top somewhat above the leaves, peduncle bracts 4— 5, (sub-)basal, the upper slightly below half-way the peduncle. Flowers: floral bracts tubular; pedicel with the basal node well above the attachment of the floral bract, longer than the ovary. Sepals: the median free, 25— 145 mm long, elliptic to (ob)ovate, obtuse to caudate, glabrous to papillose or hirsute, (rather) thin, 5— 9-veined (?3-veined in Bulbophyllum tentaculatum); the laterals free or connate along the lower margin, as long as or shorter than the median; 25— 110 mm long, (ob-)ovate to triangular, obtuse to acuminate, glabrous to papillose or hirsute, (rather) thin, 5— 7-veined. Petals 6— 16 mm long, ovate to triangular, obtuse to caudate, if caudate tip often with a thickened, globular to ellipsoid-cylindrical, glabrous to ciliolate appendage, petal otherwise glabrous; thin to thick, 3-veined (1-veined in Bulbophyllum tentaculatum). Lip mobile on a thin ligament, without auricles (with minute, retrorse auricles near the ligament in Bulbophyllum tentaculatum), undivided, 2— 8.5 mm long, oblong, ovate to sub-triangular, margins entire, glabrous to papillose or ciliate; adaxially somewhat concave near the base or not (deeply concave in Bulbophyllum tentaculatum), without ridges, surface glabrous to partly hirsute. Column with the rostellum front well receding in between the stelidia, stigma wide, without keels inside, or with a single keel on the back wall, proximally not protruding, column foot somewhat tapering towards its top or not, free part short; tip without teeth. Stelidia less than 1/2 of the length of the column, short, deltoid to triangular (more than of the length of the column and subulate in Bulbophyllum tentaculatum), with or without a small tooth along the upper margin, close to the tip, with or without an inconspicuous to distinct, rounded to obtuse wing along the lower margin. Anther abaxially with a rounded crest, front inflated and deeply concave, front margin not drawn out. Pollinia 4, with the inner approx. half as long as the outer or shorter; without appendages.
New Guinea: 18 taxa. Altogether 19 provisionally accepted taxa (30 names): from Thailand, Java east to the Pacific. West of New Guinea range extension determined by Bulbophyllum antenniferum and Bulbophyllum leysianum.
Most similar to section Hoplandra, differs in having 4 pollinia. On average section Hyalosema has distinctly larger flowers.
The following taxa in this program belong to this Section: