Oncidium fuscatum Rchb.f., Ann. Bot. Syst. 6: 763. 1863.
Type: Diar. Cuchero. Feb 1830. Detecta a nob. de Warscewicz. Hab. sp. sicc. comm. ab. ill. Lindley sub N. 128. Warscewicz s.n. (W).
Illustrated specimen: Colombia. Tolima: Municipality of Villahermosa, 1103 m. 19 December 2018. M. A. Sierra-Ariza & A. Albino-Bohórquez 117 (TOLI; LCDP voucher).
Etymology: From the Latin fuscatum “dark” in relation to the color of the flowers.
Oncidium fuscatum is found from southern Panama to Peru, at elevations from 450 to 1700 m. This species is distinguished from the other Oncidium in Colombia by the dark flowers, the orbicular lip and the callus without pronounced protuberances; a rare form with fully white flowers is known to exist.