The Pacific flatbill (R. pacificus) is sometimes still considered a subspecies of R. brevirostris.
This species measures 15 cm (5.9 in).[2] It has olive-green upperparts and green streaked breast grading to a yellowish belly and white vent. Then tail is also green. Its face is grey with a prominent white eye ring. The short, flat bill is bicolored, with the upper mandible dark grey and the lower mandible pinkish orange.
^Garrigues, Richard; Dean, Robert (2007). The Birds of Costa Rica. Ithaca: Zona Tropical/Comstock/Cornell University Press. p. 200. ISBN978-0-8014-7373-9.
^Angehr, George R.; Dean, Robert (2010). The Birds of Panama. Ithaca: Zona Tropical/Comstock/Cornell University Press. p. 234. ISBN978-0-8014-7674-7.
Skutch, Alexander F. (1960). "Eye-ringed flat-bill"(PDF). Life Histories of Central American Birds II. Pacific Coast Avifauna, Number 34. Berkeley, California: Cooper Ornithological Society. pp. 508–515.