Diplocaulobium ridleyanum (Schltr.) W.Kittr., Bot. Mus. Leafl. 30 (1984, publ. 1985) 98.
Basionym: Dendrobium ridleyanum.
Rhizome long, creeping, with relatively few roots. Pseudobulbs rather distant, 1-leaved, elongate-ovoid to conical, 2 by 0.7-0.8 cm. Leaves narrowly lanceolate, 2.5 by 0.4-0.5 cm, coriaceous, apex acute-acuminate, the very tip obtuse. Inflorescences terminal, often fasciculate, 1-flowered, together with pedicel and ovary as long as or a little longer than the leaves, spathe ?lanceolate. Flower c. 2 cm across when flattened and expanded. Dorsal sepal lanceolate, 1 cm long, apex acute. Lateral sepals with the free part similar to the dorsal sepal, mentum rather large, slightly curved, about as long as the free part. Petals linear-lanceolate, c. 1 cm long, apex acute. Lip ligulate, slightly widened near the apex, obscurely 3-lobed near the apex, the lateral lobes hardly developed, midlobe rounded, obtuse.
(after Kraenzlin, 1910 - as Dendrobium humifusum).
Colours: Sepals and petals white, lip on midlobe with purple spots and margins, at apex golden yellow.
Habitat: Presumably in seasonally dry lowland forest. Altitude 550 m.
Flowering time in the wild: Not known.
Distribution: New Guinea (endemic).
Distribution in New Guinea: Papua New Guinea (Central Province: Sogeri).
Notes: Related to Diplocaulobium chrysotropis, but the description of Diplocaulobium ridleyanum is insufficiently detailed to judge whether they are conspecific (in which case the latter name would have priority).
Cultivation: Warm growing epiphyte.