Bulbophyllum section Intervallatae Ridl., J. Linn. Soc., Bot. 31 (1896) 276
Small to medium-sized epiphytes. Rhizomes creeping; rhizome bracts thin to thick, glabrous, caducous , the veins somewhat more persistent as fibres. Roots sprouting mainly below the pseudobulbs, spreading, glabrous, slightly and finely hirsute locally. Pseudobulbs inconspicuous to distinct compared to the size of the plant, 1-leafed, with shoots sprouting at its basal node, not fused to the pseudobulb. Leaves persistent, thick, veins inconspicuous. Inflorescences sprouting from the (sub-)basal node of the pseudobulb, single, a usually short raceme with flowers distichous. Peduncle longer than the pseudobulbs, peduncle bracts 4— 9, scattered with the upper up to somewhat above half-way the peduncle. Rachis somewhat thickened or not. Flowers per inflorescence usually 1 open at a time, several open in some species; floral bracts amplexicaul, often proximally tubular (higher up in the rachis); pedicel with the basal node well above the attachment of the floral bract (sometimes only slightly above the attachment in the lowermost flower), longer than the ovary. Sepals free, the laterals 1— 1.4 times as long as the median; 12— 80 mm long, elliptic or oblong to triangular, obtuse to caudate, glabrous, rather thin to thick, 5— 11-veined. Petals 1.5— 11 mm long, (transversely) elliptic to triangular, rounded to caudate, margins entire to distally erose or denticulate, often with 3 (groups of) teeth in the top part; thin to rather thick, 1— 5-veined, surface glabrous. Lip mobile on a thin ligament, often with (in-)conspicuous, antrorse auricles close to the base, undivided, 9— 40 mm long, elliptic to oblong, to triangular (approx. obovate-spathulate in Bulbophyllum spathilingue), margins glabrous to erose or dentate; adaxially with two inconspicuous or distinct, entire to erose to dentate ridges in approx. flexural position, sometimes with two more, elongated to knob-shaped ridges close to the ligament, adaxial surface glabrous to partly or entirely coarsely papillose, irregularly verrucate to dentate; abaxial surface glabrous to somewhat corrugated. Column with rostellum front receding in between the stelidia tips, stigma small or large, with 3 keels inside (two on the front wall, a single on the back wall), proximally often more or less protruding, or with two more or less protruding teeth, column foot tapering towards its top or not, with or without inconspicuous lateral lobes next to the ligament, or with a median tooth near the ligament, free part short or absent. Stelidia 1/2 of the length of the column or shorter, deltoid to narrowly triangular, sometimes subulate, obtuse to caudate, with or without a small tooth along the upper margin, or upper margin erose, with or without a deltoid, rounded wing along the lower. Anther abaxially with a low, rounded crest, front not concave, front margin not or hardly drawn out. Pollinia 4, the inner more than half as long as the outer (less than half as long in Bulbophyllum caloglossum), with or without a single fleshy stipes.
New Guinea: 36 taxa. Altogether 47 provisionally accepted taxa (61 names): Peninsular Malaysia, Sumatra, Borneo, Sulawesi, The Philippines, New Guinea, West Pacific.
Differs from section Lepidorhiza in having glabrous roots. Section Lepidorrhiza is often larger, with larger floral bracts and an more elongated raceme. All species share papillose-rugulose-verrucate roots and a distichous raceme. Some species usually have several flowers open simultaneously per inflorescence (previously section Pachyantha Schltr). These are otherwise not very similar, all are included here.
For convenience only, and possibly not reflecting phylogenetic affinities, the section can be divided into three series:
a (section Pachyanthe) Petals entire. Flowers per inflorescence several open at a time
b Petals entire. Flowers per inflorescence 1 open at a time
c (Section Intervallatae, Section Dialeipanthe) Petals erose, or distally incised.
The following taxa in this program belong to this Section:
Bulbophyllum verruciferum var. carinatisepalum