A new species of night monkey (pictured) is one of eight new mammals found during an expedition to northern Peru's Tabaconas Namballe National Sanctuary, scientists announced recently.

A team of Mexican and Peruvian biologists found this "new heaven of unknown biodiversity" during a 2009-2011 expedition, according to a press statement.

Rarely seen and little-studied, night monkeys are listed as vulnerable by the International Union for Conservation of Nature (IUCN) and endangered by the Peruvian government, making the new discovery especially notable.The as yet unnamed new species was found close to the border of Ecuador, said expedition co-leader Gerardo Ceballos, of the National Autonomous University of Mexico.

Compared with two other species of night monkey in the region, the new one has a more uniform color and smaller skull.

Tabaconas Namballe National Sanctuary's cloud forests provide shelter to at least 85 species of mammals, 326 species of birds, and 23 species of reptiles and amphibians—numbers that may grow as explorers delve deeper into the region.

The sanctuary contains a wide array of habitats—from rain forests to grasslands—condensed into roughly 70,000 acres (28,000 hectares), Ceballos said.

However, deforestation throughout much of South America may affect undiscovered species, Ceballos said.

"The habitat is very valuable," he said, "even without knowing the species that are there."


Common Shrew Opossum

Almost twice the size of its closest relative, this new species of common shrew opossum is the largest yet found in the region.

Occasionally known as a marsupial shrew, common shrew opossums are usually rat-size and have well-defined ears, long tails, and long, pointed snouts.

"It belongs to [a] marsupial family with only three other species," Ceballos said.


Enigmatic Porcupine

Discovered due to its large size and unusually dark fur, this new species—called an enigmatic porcupine—differs from its counterparts in another way: quill size.

Unlike other porcupines in the region, the new species' quills are "extremely long," Ceballos said.

Locals also told the team that there may be more porcupine species awaiting discovery. "They showed the skin of an entirely different species we have never seen," he said.


Small-Eared Shrew

This new species of small-eared shrew is still in the process of being named by Ceballos and his team. Much smaller than its relative the marsupial shrew, the small-eared shrew is an insect-eater distinguished by extremely small eyes and barely visible ears.

Not much is known about small-eared shrews in general, which are classified as data deficient by the IUCN.