Bulbophyllum section Brachypus Schltr., Repert. Spec. Nov. Regni Veg. Beih. 1 (1912) 700
Small to medium-sized epiphytes. Rhizomes (rather) short-creeping; rhizome bracts thin, approx. glabrous to minutely colliculate, caducous (with the veins slightly more persistent). Roots sprouting mainly below the pseudobulbs, glabrous or slightly and minutely hirsute locally. Pseudobulbs conspicuous compared to the size of the plant, 1-leafed, with shoots sprouting at its basal node and free, or fused to the pseudobulb over a very short distance only. Leaves persistent, thick, veins inconspicuous. Inflorescences sprouting at or somewhat above nodes along the length of the rhizome, usually densely fasciculate, 1-flowered. Peduncle shorter than to approx. as long as the pseudobulbs (approx. as long as the leaves in Bulbophyllum ialibuense), peduncle bracts 24, scattered along the peduncle. Flowers per sympodium 1 open at a time; floral bracts tubular; pedicel with the basal node well above the attachment of the floral bract, approx. as long as the ovary or longer. Sepals free, or the laterals (partly) connate, or all three (partly) connate; the laterals not or hardly longer than the median (the laterals up to 1.2 times as long as the median in Bulbophyllum ialibuense); 852 mm long, elliptic to ovate-triangular, obtuse to short-acuminate, margins entire, glabrous (minutely papillose-ciliolate in Bulbophyllum phaeoglossum), thin to thick, 39-veined, surface glabrous or (finely) papillose to hirsute adaxially. Petals fused to the column over a short distance near the base, either over their entire width, or along the upper margin only (free in the group of Bulbophyllum lineolatum, see below), 38 mm long, rhombiform, oblong, or elliptic to triangular, truncate to acute, margins approx. entire, glabrous to papillose to ciliolate; thin, 1-veined, glabrous (adaxial surface finely papillose in Bulbophyllum calceilabium). Lip mobile on a thin ligament, without auricles near the ligament, undivided, 2.58 mm long, elliptic to (ob-) ovate, oblong, or hastate, margins approx. entire, glabrous to papillose or ciliolate; adaxially without ridges, or with two (more or less converging) ridges in approx. flexural position, surface approx. glabrous to papillose; abaxial surface glabrous, or with a distinct, finely to coarsely papillose or hirsute patch in the middle part (often combined with an approx. glabrous adaxial side). Column with rostellum front receding in between the stelidia, stigma slit-like to wide, rounded, without keels inside, usually not protruding proximally (protruding in Bulbophyllum ialibuense, some of the group of Bulbophyllum lineolatum), column foot not or hardly widening nor thickening towards its top, free part short, without lateral teeth at the tip (with small, patent lateral teeth in Bulbophyllum variculosum, Bulbophyllum wollastonii). Stelidia shorter to distinctly longer than 1/2 of the length of the column; distinct, triangular to subulate, or narrowly oblong, with or without a patent to antrorse deltoid, obtuse tooth along the upper margin, with at most a slight, rounded widening present along the lower (with a deltoid, obtuse wing in Bulbophyllum variculosum). Anther abaxially with a high rounded crest, front not concave, front margin not drawn out. Pollinia 4, with the inner more than half as long as the outer, without appendages. Colours: Flowers usually white or yellowish or greenish, with or without purple markings, or flowers largely purple; lip bright yellow in some species. .
New Guinea: 19 taxa. Altogether 20 provisionally accepted taxa (22 names): New Guinea, West Pacific.
Diagnostic, because best grouping overall similar species together, are the petals which are proximally fused to the column. Generally, the species are characterized by a short rhizome with clustered pseudobulbs, and short-peduncled flowers. Many species have a distinctly thickened and widened rostellum, sitting as a shield-like structure between the stelidia. The taxonomic value of this character needs investigation, as does the precise delimitation of the section. The inflorescence of Bulbophyllum ustusfortiter is much contracted, and so is the distance between the floral bract and the pedicel node.
In general aspect grading into section Polymeres through species such as Bulbophyllum bombycinum, Bulbophyllum maxillaroides which are here included in the latter. Section Brachypus is kept separate to accomodate a suite of species generally without, or with an indistinctly widened and laterally toothed or winged column foot.
Morphologically, the group of Bulbophyllum lineolatum (Bulbophyllum apiculatum, Bulbophyllum blepharopetalum, Bulbophyllum latibrachiatum, Bulbophyllum lineolatum, Bulbophyllum wollastonii) straddles section Polymeres and section Brachypus in the shape of the column foot. The petals are not fused to the column. The flower shape, in particular the narrowly oblong, strap-shaped, obtuse, stelidia suggests phylogenetic affinity of the species. The group is provisionally included in section Brachypus.
The following taxa in this program belong to this Section:
Bulbophyllum latibrachiatum var. epilosum