A black and white monkey that lives exclusively in Vietnam is in severe danger of dying out, the International Primatological Society has warned.
Hunting has pushed the animal back into a few strongholds
Only about 300 Delacour's langurs are alive today, and experts fear they could be completely extinct by 2014 if the current rate of decline continues.
The monkeys are being pushed to the brink by hunting for the Chinese traditional medicine trade.
However, conservationists say swift action now could save the species.
The Delacour's langur (Trachypithecus delacouri) is a leaf-eating monkey which has an unusually long and bushy tail. It is also one of the most endangered primates in the world.
Hunting has forced the animal into a few extreme strongholds, where steep limestone cliffs grant a little protection from poachers.
Poachers covet the monkeys for their bones, organs and tissues, which are used in traditional medicines.
Development is placing an additional pressure on the fragile species by serving to isolate already small sub-populations. This means that if the main breeding male dies, the whole sub-population is at risk of fading away, because no new males can reach the group.
"We have 19 isolated populations," said Tilo Nadler, Vietnam Country Representative for the Frankfurt Zoological Society. "And 60% of the whole population lives in isolated sub-populations of less than 20 animals."
The Delacour's langur is so rare that it was not described by science until 1932, and it was another 50 years before anyone did any comprehensive research into the distribution and habitat of the species.
In the early 1990s, about 600 of the animals were found in the limestone mountain ranges that cover an area of about 5,000 sq km in northern Vietnam.
However, since then the species has taken a dramatic nose-dive. "Since 1992, around 300 animals have disappeared," Dr Nadler told BBC News Online. "So in about 10 years, 50% of the population has disappeared."
However, the monkey has reached the attention of various conservation groups, who are determined to see it survive.
"The Delacour's langur is in the top 25 of the critically endangered primate list," said Russell Mittermeier, president of Conservation International. "But the good thing about the Delacour's is that people are beginning to pay attention to it, and it does have some protected areas."
Conservation efforts are centred on two national reserves in northern Vietnam.
In Van Long National Reserve, created three years ago, approximately 70 individuals live in three separate populations.
"We have built five rangers stations [in the Van Long Reserve] and our organisation pays for about 20 rangers to protect the animals," said Dr Nadler. "This is working well and the population is increasing.
"If there is no hunting pressure, then the population will increase very fast."
Dr Mittermeier is also a fan of tourism as a method of boosting conservation.
"I'm an advocate of tourism in helping to conserve primates," he told BBC News Online. "I think it is the only alternative we have that is going to generate significant income quickly.
"I think tourism has great potential in Vietnam, and very often you can do it as high end tourism, where you get fewer people and bigger returns."
Dr Mittermeier thinks that appealing to people's bird-watching - or "twitcher" - instincts may be the best way forward.
"I think that life-listing primates could become a new sport," he said. "A lot of people are box-tickers.
"We are going to publish several life-lists of primates, and we are going to try to stimulate a little competition."
Whatever it takes, both Russell Mittermeier and Tilo Nadler hope that the international community can steer the Delacour's langur away from the knife-edge.
Dr Nadler concluded: "We have a limited window of opportunity to save them, and we hope the international community will rally around this incredible monkey."