Bulbophyllum colliferum

Smith, J.J., Nova Guinea 12, 1 (1913) 92, t. 25, fig. 76
Schlechter, R., Repert. Spec. Nov. Regni Veg. Beih. 21 (1928) t. 299, fig. 1148, as Bulbophyllum papulilabium Schltr.
Schlechter, R., Repert. Spec. Nov. Regni Veg. Beih. 21 (1928) t. 299, fig. 1147, as Bulbophyllum niveosulphureum Schltr.
Vermeulen, J.J., Orchid Monogr. 7 (1993) 128, fig. 81, pl. 4b
O'Byrne, P., Lowland Orchid. Papua New Guinea (1994) 480, fig.