The Marca's marmoset (Mico marcai) is a species of marmoset that is endemic to the Amazon, in the Aripuanã-Manicoré interfluvium in Brazil.[4] It is virtually unknown; in 2008 the IUCN noted that it had never been seen in the wild,[2] though it has been observed since then.[5][6] Probably, Mico manicorensis will be considered a synonymous of M. marcai.[4]