Marañon Crescentchest is a tiny songbird, endemic to the Marañón Valley of northwestern Peru and southern Ecuador. This species is olive above and tawny below, with a dark chest band and a boldly striped black and buff head. Marañon Crescentchest is quite similar to Elegant Crescentchest (Melanopareia elegans) of the Pacific slope of southwestern Ecuador and northwestern Peru, but Marañon is larger with a longer tail and has more richly colored underparts and silver edging to wing coverts instead of the rufous edging in Elegant. Marañón Crescentchest can be found in scrub woodlands within its tiny range between 200 and 750 m in elevation. Very little is known about the natural history of this attractive species.