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. Last Updated: 07/27/2016

Researcher Finds Tiny Amazon Monkeys

RIO DE JANEIRO, Brazil -- For most scientists, discovering a new species is a rarity. For Marc Von Roosmalen, it's almost routine.

Two of Roosmalen's latest discoveries - a couple of squirrel-sized monkeys found in an obscure corner of Brazil's Amazon - were announced Saturday by Conservation International.

Roosmalen, a Dutch primatologist at Brazil's Amazon National Research Institute, says he has found 17 more monkeys he believes are new to science, as well as five new birds and two plants.

"I have to stop doing surveys because I keep coming up with something else and I don't have time to write them all up,'' Roosmalen said by telephone from the jungle city of Manaus, 2,900 kilometers northwest of Rio de Janeiro.

One of the new monkeys is the Callithrix Manicorensis, or Manicore Marmoset, which has a silvery white upper body, a light gray cap on its head, yellow to orange underparts and black tail. The other, Callithrix Acariensis, or Acari Marmoset, has a snowy white upper body and under parts, a gray back with a stripe running to the knee and a black tail with a bright orange tip.

An average adult of both species measures 22 centimeters with a 38-centimeter tail and weighs around 350 grams.

The monkeys are named after the Manicore and Acari Rivers, the Amazon River tributaries near where they were found about 300 kilometers from Manaus, where local residents kept them as pets.

Formal scientific descriptions of the pair will be published in the scientific journal Neotropical Primates in the next few weeks.

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 and the dozens of rivers that criss-cross it to creating natural barriers that tend to isolate the species.

Roosmalen said he found the two while searching for the habitat of another small monkey, which a local man brought to his door in the jungle city of Manaus, because he knew Roosmalen and his wife care for orphaned animals. 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. Even among our closest relatives, the primates, which have been closely studied, there are still new species to be discovered,'' said Russell Mittermaier, president

of Conservation International and a co-author of both scientific descriptions.