Stephen Nash's titi as on the underside of the species' limbs. It is 28 inches long, although 17 inches is taken up by the titi's tail. Stephen Nash's titi 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. It was discovered by Marc van Roosmalen in 2001 when local fishermen brought specimens to his breeding center. It was described in 2002. It was named in honor of Stephen D. Nash, an illustrator for Conservation International,
Collared titi is found west of the Río Purús to the Yavarí River. The collared titi is seen most frequently in well-developed, tall forest with a closed canopy, usually over terra firme, but not exclusively so. The species also enters extensive várzea forest, especially if the forest is tall and well-developed. Such várzea forest contrasts with the habitat needs of the coppery titi, which also uses várzea forest and more commonly so. But the coppery titi survives in low, vine-covered, "poor" forest where the collared titi is rarely found. It is also known from some gallery forest, north of the Vichada River,