September 9, 2009--It may look like a ferocious mutant from the city sewer. But this newfound species of giant woolly rat is a docile denizen of the forests of Papua New Guinea.

On a chilly night earlier this year, biologists Kristofer Helgen and Muse Opiang were trekking through high-elevation rain forests on the inactive volcano Mount Bosavi when a local tracker pointed out a cat-size rodent walking on the forest floor.

Helgen, of Washington D.C.'s National Museum of Natural History, had been hoping to find giant rats, which are known to live in other parts of the Pacific.

(Related: "New Giant Rat, Pygmy Possum Discovered.")

But "what was totally unexpected was the animal [we found] was tractable, and fairly tame—it wasn't afraid of us at all," he said. (See photos of more new species found in Papua New Guinea in 2008.)

With its silvery, shaggy fur, the 3-foot-long (0.9-meter-long) Bosavi woolly rat is "quite a handsome beast," added Helgen, also a National Geographic emerging explorer. (The National Geographic Society owns National Geographic News.)

Including the rat, the first formal scientific expedition onto the 8,858-foot (2,700-meter) volcano—filmed for the BBC One program Lost Land of the Volcano between January and March 2009—unearthed 40 potentially new species.

--Christine Dell'Amore