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Bulbophyllum section Macrouris Schltr., Repert. Spec. Nov. Regni Veg. Beih. 1 (1912) 703. Type species: Bulbophyllum macrourum Schltr.
Small to medium sized epiphytes. Rhizomes creeping, straggling, or patent to pendulous; rhizome bracts thin, papillose to sometimes glabrous, caducous but veins thick, persistent as fibres. Roots sprouting mainly below the pseudobulbs, or below the older pseudobulbs only, spreading (growing over or alongside the rhizome towards the substrate in Bulbophyllum pidacanthum, Bulbophyllum scopa), densely papillose-rugulose-verrucate (almost glabrous in Bulbophyllum dekockii). Pseudobulbs conspicuous to minute compared to the size of the plant, 1-leafed, with shoots sprouting from its basal node and free, not fused to the pseudobulb. Leaves persistent, thick, veins inconspicuous. Inflorescences sprouting from the basal node of the pseudobulb, sometimes at a short distance above the subtending rhizome bract attachment, single, rarely 2 together, 1-flowered or racemose with flowers spirally arranged. Peduncle short and little protruding from the subtending rhizome bract, to long and with the top well above the leaves, peduncle bracts 3—8, scattered but most in the basal half of the peduncle. Rachis, if present, not thickened. Flowers per inflorescence 1—many open at a time; floral bracts not amplexicaul (amplexicaul in the upper flowers of species with a few-flowered inflorescence); pedicel with the basal node well above the attachment of the floral bract, distinctly longer than the ovary (as long as or slightly longer than the ovary in Bulbophyllum myon, Bulbophyllum trifilum). Sepals free, the laterals sometimes adherent to connate along their lower margin, 1—3 times as long as the median; 3—120 mm long, elliptic to triangular, acute to caudate (also rounded in Bulbophyllum subpatulum), glabrous, (rather) thin, top thickened or not; 1—3-veined (5-veined in Bulbophyllum dekockii). Petals 1—7 mm long, elliptic to (ob-)ovate, emarginate to acuminate, margins entire to (distally) erose; thin, 1-veined (3-veined in Bulbophyllum dekockii), surface glabrous. Lip mobile on a thin ligament, without auricles near the ligament, undivided, 1.2—6 mm long, ovate to oblong, sometimes sub-panduriform, margins glabrous to papillose to sometimes ciliolate (also ciliate in Bulbophyllum orbiculare); adaxially without ridges, or with a median ridge and/or with two (distinctly converging) flexural ridges (two short ridges in non-flexural position in Bulbophyllum fonsflorum, Bulbophyllum olivinum), surface approx. glabrous. Column with rostellum front approx. level with the stelidia tips or somewhat receding in between these, stigma large, without keels inside, proximally protruding or with a distinct tooth, column foot tapering towards its top, free part long, short or virtually absent; with or without a small median callus just short of the ligament (with auricles near the ligament in Bulbophyllum sceliphron). Stelidia shorter to longer than 1/2 of the length of the column; short but not vestigial, approx. deltoid (long and subulate in Bulbophyllum grammopoma, Bulbophyllum sceliphron), sometimes denticulate or with a tooth along the upper margin, sometimes with a deltoid tooth along the lower. Anther abaxially with a (low) rounded crest, front not concave, front margin drawn out into a small, triangular beak or not. Pollinia 2, (4 with the inner less than half as long as the outer in Bulbophyllum callichroma, Bulbophyllum chloranthum); without appendages.
Maluku, New Guinea, West Pacific.
Genus Bulbophyllum section Macrouris contains 28 accepted species (51 names); in New Guinea 23 species.
Lowland forest to montane forest. Altitude 0 - 3000 m.
Revised in Vermeulen (1993: 89); his Bulbophyllum Section Macrouris series C, with 3 species, is excluded (see Bulbophyllum section Imitatores).
Bulbophyllum section Macrouris contains the following 23 species and 4 subspecies:
Bulbophyllum levatii subsp. mischanthum
Bulbophyllum olivinum subsp. linguiferum
Bulbophyllum orbiculare subsp. cassideum
Bulbophyllum trifilum subsp. filisepalum