In 1923 explorers in what is now known as the Democratic Republic of Congo brought out a specimen of a monkey with grayish-green fur, a red face and webbed digits. Dubbed Allen's swamp monkey, or Allenopithecus nigroviridis, the primate was the most recent new genus of primate discovered--until now. Scientists have determined that a monkey previously identified as a new species from photographs deserves its own genus name.

Based on the photographs, taxonomists had thought that the grayish-brown monkey with its long, curling tail and the crest atop its head was a new species of mangabey, though it lacked that animal's distinctive call. That assessment changed once they obtained a specimen from a Tanzanian farmer, who had trapped a raiding individual. By studying the mitochondrial and Y chromosome DNA as well as other genetic data from the animal, Link Olson of the University of Alaska Museum determined that it was more closely related to savanna baboons than mangabeys. Yet a cranial analysis by primatologist Eric Sargis of Yale University found that it lacked many of the typical features of such baboons. The researchers decided that the creature was sufficiently different from known primates to warrant a new genus. They dubbed it Rungwecebus kipunji for the mountain in southwestern Tanzania that it primarily calls home, along with the local name for the shy, arboreal creature.

"This is exciting news because it shows that the 'age of discovery' is by no means over," says William Stanley of the Field Museum, a co-author of the report detailing the findings published online yesterday by Science. Unfortunately, only 20 groups of roughly 30 individuals each are known to exist in just two highland areas of Tanzania--Mount Rungwe and the Ndundulu Forest--making its future uncertain. Indeed, hunted by crowned eagles and by humans--both for its meat and as punishment for its foraging raids--the new monkey may face imminent extinction. After all, notes primatologist John Robinson of the Wildlife Conservation Society, "it would be the ultimate irony to lose a species this unique so soon after we have discovered it."