Stephen Nash's titi (Plecturocebus stephennashi), also known as just Nash's titi or Stephen Nash's monkey, is a species of titi, a type of New World monkey, endemic to the eastern bank of the Purus River in Brazil.[1][2][3] It was discovered by Marc van Roosmalen in 2001 when local fishermen brought specimens to his breeding center.[4] It was described in 2002.[5] It was named in honor of Stephen D. Nash, an illustrator for Conservation International, the organization that funded van Roosmalen's work.[5] The monkey is largely silver with a black forehead and red sideburns and chest, as well as on the underside of the species' limbs.[4][5] It is 28 inches long, although 17 inches is taken up by the titi's tail.[5]