The Maranon Spinetail is a range-restricted furnariid of the Maranon Valley in Peru and adjacent Ecuador. The species prefers deciduous woodland, but also inhabits scrub and humid forest undergrowth, and is found between 500 and 1100 meters in elevation within its tiny range. Brown above and grayish below with a pale gray-brown supercilium and rufous wings and tail, this bird is a typical Synallaxis spinetail in structure and coloration. It has been considered conspecific with the Plain-crowned Spinetail, but is much grayer below than that widespread species. Maranon Spinetail can be detected by its high, nasal, two-part call that is repeated. Land clearing in the Maranon Valley has proven detrimental to this species, which is now classified as "vulnerable" by the IUCN Red List.