It stands just three feet tall, is covered in long brown fur, and communicates using a distinctive honking bark.
It may look and behave like any other monkey, but to scientists this new species of African primate represents one of the most important finds in a generation.
A study of the species living in the remote mountain forests of Tanzania has found that it belongs to its own unique classification or genus - the first new primate genus for 83 years.
The discovery of the monkey was first announced last year, but it is only now that scientists have been able to study it in fine enough detail to realise its significance.
"The discovery of a new primate species is an amazing event, but the discovery of a new genus makes this animal a true conservation celebrity," said Tim Davenport of the Wildlife Conservation Society in New York. "The scientific community has been waiting for eight decades for this to happen and now we must move fast to protect it," said Dr Davenport, who led the discovery team.
The monkey is known locally as kipunji but scientists have given it the formal name of Rungwecebus kipunji after the volcanic mountain of Rungwe where the creature lives in forests that are fast disappearing through illegal logging.
Genetic analysis of the animal's DNA and a detailed scrutiny of its skull and skeleton have confirmed that it is more closely related to baboons than to the mangabey monkeys which it superficially resembles.
"One way of showing the significance of this discovery is by pointing out that it's the first time we have found such a primate species in more than 80 years," Dr Davenport said.
"We have shown how different this animal is from anything else that has been discovered. It's really rather extraordinary," he said.
William Stanley of the Field Museum in Chicago, which houses the only dead specimen of the species, said that the study, which is published today in the journal Science, was an extraordinary example of how much there is still to discover about life on Earth.
"This is exciting news because it shows that the age of discovery is by no means over," Dr Stanley said.
Another member of the team, Link Olson of the University of Alaska Museum in Fairbanks, said: "Finding a new genus of the best-studied group of living mammals is a sobering reminder of how much we have to learn about our planet's biodiversity."
Scientists were first alerted to the prospect of a new species of monkey after interviewing local villagers about the region's wildlife.
The villagers hunt wild animals for food - known as bushmeat - and some hunters referred to a monkey they called kipunji. But scientists were not sure whether this was a mythical "spirit" creature or a real animal living in the remote highland forests.
After several excursions to the mountain, the biologist Sophy Machaga managed to make a sighting, and Dr Davenport later took good enough photographs for it to be identified as a new species. But it was not until the scientists managed to study a dead monkey caught in a maize farmer's trap that it became clear just how different the species was from any primate known to science. A DNA analysis confirmed that the animal was genetically distinct from any other group and that it should be reclassified in its own separate genus. "This study is a textbook example of how a variety of individuals and institutions spanning the globe can work together to significantly improve our understanding of the biodiversity of this planet," Dr Stanley said.
"Within hours of Sophy Machaga creeping though the rain-soaked forests of Rungwe documenting the behaviour of a troop of kipunji, Link Olson in Alaska was trudging through the snow in minus 20C to his molecular lab in Fairbanks, more than 8,500 miles away," he said.
The monkey is covered in long, greyish brown hair with off-white fur on its belly and the tip of its long, curly tail. It sports a crown of long, erect fur on its head and adults call to each other using a distinctive honk-bark.
It lives in a dwindling region of highland forest some 12 hours journey by road from Dar es Salaam and a day's trek up the mountain from the nearest village, Dr Davenport said.
Kipunji monkeys live in groups of 30 to 36 and are omnivores, feeding on leaves, shoots, flowers, bark, fruit, lichens, moss and insects.
Dr Davenport said that illegal logging was forcing the animals out of their natural habitat to raid local crops. He added "I imagine the forest has been reduced and these groups of kipunji are being squeezed. I don't imagine that there are more than 700 or 800 individuals left," he said.Reuse content