Distribution map of Bulbophyllum rubromaculatum
Bulbophyllum nigrescens Schltr., floral analysis, R. Schlechter in Repert. Spec. Nov. Regni Veg. Beih. 21 (1928) t. 289, fig. 1106
Bulbophyllum nigrescens Schltr., herbarium sheet, Schlechter 17707 (isotype specimen K), photo copyright the Board of Trustees of the Royal Botanic Gardens, Kew