Diplocaulobium gracilicolle (Schltr.) W.Kittr., Bot. Mus. Leafl. 30 (1984, publ. 1985) 98.
Basionym: Dendrobium gracilicolle.
Rhizome very short. Pseudobulbs crowded, 1-leaved, at the base fusiform, upper part long and slender, total 12-17 cm long, near the base 0.4 cm wide. Leaves narrowly linear, 20-25 by 0.3-0.4 cm, apex minutely unequally bilobulate. Inflorescences 1-flowered. Pedicel and ovary 3 cm long. Flower c. 5 cm across. Sepals in basal part lanceolate, upper part filiform, 3.3 cm long; mentum conical, c. 0.3 cm long, obtuse. Petals in basal part obliquely linear-lanceolate, in upper part filiform, a little shorter than the sepals. Lip panduriform, 1 by 0.35 cm, with two keels extending from the base to halfway the terminal lobe, the keels papillose in basal part, subcrenulate towards the apex, between the keels with a swollen median line, starting at c. 1/3 above the base, extending to c. 1/3 below the apex; terminal lobe with a very short claw, the blade suborbicular-elliptic, 0.33 cm wide. Column short; column-foot slightly incurved, ligulate, 0.3 cm long.
(after Schlechter, 1919).
Colours: Not known.
Habitat: Not known.
Flowering time in the wild: Not known.
Distribution: New Guinea (endemic).
Distribution in New Guinea: Papua New Guinea (Sandaun Province).
Notes: Diplocaulobium gracilicolle should be easy to recognize by the very long and narrow leaves.