Bulbophyllum arsoanum J.J.Sm., Repert. Spec. Nov. Regni Veg. 11 (1912) 276
Type: Gjellerup 640 (holo BO)
Pseudobulbs close together; base short, swollen, more or less narrowing in a neck, somewhat laterally compressed, above many-grooved, c. 1.3 by 0.35 cm at the base; apex slightly over 0.2 cm wide, initially enclosed by sheaths. Leaf erect, linear-lanceolate, apiculate-acute; base rather long contracted in a canaliculate petiole; upper side on either side of the midrib grooved; underneath obtusely prominent, convex, fleshy, c. 13.5 by 1.5 cm. Inflorescences 1-flowered; peduncle thin, c. 1.1 cm long. Floral bract tubular, keeled, acuminate. Flower medium size. Median sepal lanceolate; base covered by the upper margin of the lateral sepals; basal part slightly rhombic-dilated, obtuse, obtusely conical-apiculate, concave; apex inside convex finely warty; nerves 3 dorsally prominent, in the middle very minutely erose, c. 1.3 by 0.35 cm. Lateral sepals lanceolate, falcate, shortly apiculate-acuminate, concave, dorsally convex; nerves 3, dorsally subprominent, c. 1.6 by 0.46 cm. Petals very small, 1-nerved, 0.35 by 0.1 cm at base and apex; base dilated; towards the middle constricted; above spathulate-dilated, obtuse; upper part papillose-verrucose and papillae clavate. Lip mobile, at c. 2/5 above the base obtusely angled, recurved, fleshy, glabrous, in total 0.55 by 0.25 cm in the basal part when not flattened, in the front part 0.34 by 0.16 cm; basal part concave, with oblique, erect, dilated, rounded margins, concave, inside with 2 longitudinal, in the basal part secund keels, margins decurrent, to the top vanishing; underneath convex; front part straight, oblong-triangular, obtuse, convex. Column curved, 0.33 cm long, the apex on either side of the anther with a small tooth, the base below the stigma with a decurved, in lateral view acute callus; stelidia porrect, shorter than the anther, triangular, subulate-acuminate, the upper margin with a tooth; stigma longitudinal; column-foot making an almost straight angle with the ovary, obtuse, linear, incurved, with free apex, truncate, 0.25 cm long. Anther cucullate, ovate-cordate, 0.13 cm long; apex elongated, obtuse, triangular, above convex underneath concave. Ovary 6-grooved, sparsely very minutely furfuraceous-finely punctate, 0.5 cm, long; pedicel c. 4.5 cm long, at 0.3 cm above the base articulate. (After Smith, 1916)
Colours: Flower yellowish-white, light violet punctuate.
Habitat: Epiphyte in lowland forest; 60-450 m.
Flowering time in the wild: May, August.
Distribution: Malesia (New Guinea).
Distribution in New Guinea: Papua (Indonesia); Papua New Guinea; see map 96-142M.jpg.
Cultivation: Warm growing epiphyte.