2 New Monkey Species Discovered in Remote Area of Brazil’s Amazon

Two squirrel-size monkeys have been discovered in a remote corner of Brazil’s Amazon, a region rich with biodiversity because of the dozens of rivers there, a conservation group said Saturday.

Washington-based Conservation International announced the findings of Marc Von Roosmalen, a scientist from Brazil’s Amazon National Research Institute.

The two monkeys, discovered in northwestern Brazil about 1,600 miles northwest of Rio de Janeiro, are the Callithrix manicorensis, or Manicore marmoset, and the Callithrix acariensis, or Acari marmoset.

An average adult of each species measures 9 inches, with a 15-inch tail, and weighs about 12 ounces.

The Callithrix manicorensis has a silvery white upper body, a light gray cap on its head, yellow to orange underparts and a black tail. The Callithrix acariensis has a snowy white upper body and underparts, a gray back with a stripe running to the knee and a black tail with a bright orange tip.

The monkeys are named after the Manicore and Acari rivers, the Amazon River tributaries near where they were found. Residents of the region keep them as pets.

Formal scientific descriptions of the pair will be published in the upcoming edition of the scientific journal Neotropical Primates.

Beyond differences in coloration, the two have genitalia that are markedly different from other related species, Roosmalen said.

He attributed the abundant biodiversity in the region to the dozens of rivers that crisscross it, creating natural barriers that tend to isolate the species. Monkeys that may share a common ancestor developed into separate species over several million years.

Roosmalen said he found the two while searching for the habitat of another small monkey. That monkey, whose discovery was announced in 1997, turned out to be the world’s second smallest.

“These findings remind us of how much we have yet to learn about the Earth’s diversity of life,” said Russell A. Mittermaier, president of Conservation International and a co-author of both scientific descriptions. “Even among our closest relatives, the primates--which have been closely studied--there are still new species to be discovered.”