The Red-mantled Saddle-back Tamarin is native to forests of the upper Amazon Basin in Peru and Ecuador.
It used to be considered a subspecies of the Brown-mantled Saddle-backed Tamarin, Leontocebus/Saguinus fuscicollis,
of north-eastern South America, from the Andes through to Colombia and eastern Brazil but, along with some other saddle-back tamarins,
was separated to species status. Along with the other Saddle-backs, it suffers from habitat destruction (mainly for logging/agriculture).