Bulbophyllum section Codonosiphon Schltr., Repert. Spec. Nov. Regni Veg. 10 (1911) 178
Minute to medium-sized epiphytes. Rhizomes long- to short-creeping, straggling, shortly ascending, patent to stiffly pendulous; rhizome bracts thin, approx. glabrous to minutely colliculate, caducous including the veins, or with the veins slightly more persistent. Roots usually sprouting mainly below the pseudobulbs, sometimes sprouting from nodes along the length of the rhizome, spreading; in species with patent to pendulous rhizomes mainly near to the base of the rhizomes, growing backwards towards the substratum over or alongside the rhizome, 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 part or most of the length of the latter. Leaves persistent, thick, veins inconspicuous. Inflorescences sprouting at nodes along the length of the rhizome; single to densely fasciculate, 1-flowered. Peduncle shorter than the pseudobulbs to longer than the leaves, peduncle bracts 1—5, scattered but the upper below half-way 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, shorter to distinctly longer than the ovary. Sepals free, sometimes the laterals connate along their lower margin (all three proximally connate in Bulbophyllum codonanthum, Bulbophyllum campanulatum); all of approx. equal length, 5—65 mm long, elliptic, oblong, (ob-)ovate to triangular, obtuse to acuminate, margins entire, glabrous (ciliolate in Bulbophyllum holochilum), (rather) thin, 3-veined, surface glabrous (adaxially finely papillose-hirsute in Bulbophyllum codonanthum, Bulbophyllum campanulatum). Petals 0.7—10 mm long, elliptic, oblong, (ob-)ovate, rhombiform, triangular (with or without drawn-out top part, often downwards falcate, obtuse to caudate, margins entire to erose, glabrous to papillose (ciliate in Bulbophyllum holochilum, Bulbophyllum scyphochilus); thin, 1-veined, surface glabrous. Lip (partly) immobile because fused to or firmly appressed to the column foot over a smaller or larger area (mobile on a thin ligament in e.g. Bulbophyllum caudipetalum, Bulbophyllum xanthoacron), this area in front bordered by a thin, transverse, approx. straight (not concave or notched) ridge which is appressed against the face of the column foot, often with two patent or slightly retrorse auricles where the ridge meets the lip margin, 3.5— 80 mm long, elliptic, oblong, (ob-)ovate to spathulate, often unguiculate, margins entire, glabrous to papillose or ciliolate (with long hairs in Bulbophyllum pyroglossum); adaxially usually without ridges, immediately in front of the transverse ridge ( the narrow claw, if present) concave, beyond this deeply concave to distinctly convex, surface approx. glabrous to partly or entirely papillose or shortly hirsute (with long hairs in Bulbophyllum pyroglossum); abaxial surface glabrous to partly or entirely papillose or shortly hirsute. Column slightly to distinctly incurved, with rostellum front (somewhat) receding in between the stelidia, stigma narrow, without keels inside, proximally not protruding, column foot widening and thickening towards its top, free part absent or short. Stelidia usually shorter than 1/2 of the length of the column; approx. deltoid to triangular, often erose or with short or long (longer than the stelidia themselves) teeth along the upper margin, often with one patent, deltoid to triangular major tooth along the lower margin; between this and the stelidia tips margin often erose or with teeth as along the upper margin. Anther abaxially with a (low) rounded crest, front not concave, front margin somewhat drawn out or not. Pollinia 4 (always?), the outer often concave, more or less hiding the inner, the inner more than half as long as the outer; without appendages.
New Guinea: 70 taxa. Altogether 76 provisionally accepted taxa (90 names): Borneo, Sulawesi, Maluku, New Guinea, Pacific.
The column and lip are often described as fused over a large surface. It is only true in some species, in others the fused area is small, in again others the connection consists of a thin ligament only. The character ‘lip fused to the column foot’ is incorrectly regarded as diagnostic for the group (Brieger 1978, Garay & Kittredge 1985). More characteristic is the presence of a transverse ridge near the base of the lip, often in between two auricles. In species in which the connection between lip and column foot consists of a thin ligament only, the proximal face of this ridge is firmly pressed to the face of the column foot because the ligament is very short. Section Piestobulbon has a similar ridge on the lip; the differences are given below the latter.
A division into series is possible. The characters used are largely arbitrary, and most series accommodates suites of species assumedly of various phylogenetic origins within the section.
a (section Codonosiphon s.s.)
All three sepals proximally fused.
Bulbophyllum codonanthum, with fused sepals, shows marked similarity to Bulbophyllum geniculiferum J.J. Sm., and Bulbophyllum kelelense Schltr. (series c), with free sepals.
b (section Trachychilus)
Median sepal free, laterals fused.
Bulbophyllum humile Schltr., and Bulbophyllum pendens J.J. Verm., with fused lateral sepals, shows similarity to Bulbophyllum kelelense Schltr, and Bulbophyllum stictanthum Schltr. (series c) respectively, with free lateral sepals.
c (section Coelochilus, section Scaphochilus)
All sepals free. Lip distally convex, or somewhat concave but not truly saccate
d (genus Saccoglossum)
All sepals free. Lip deeply concave over its entire length, saccate.
Most species have a more or less pendulous rhizome, Bulbophyllum takeuchii has a creeping rhizome with clustered pseudobulbs.
The following taxa in this program belong to this Section: