Hunting and deforestation has led to a continued decline in the species
Biologists from a Cambridge-based conservation group have discovered a new sub-population of the critically endangered Tonkin snub-nosed monkey.
The scientists, working for Fauna and Flora International, found up to 20 monkeys in a remote forest in Vietnam.
The team said the sighting offered a ray of hope because it included three infants, suggesting they were breeding.
The monkey can only be found in Vietnam and until now, fewer than 250 of them were thought to exist.
Fewer than 250 Tonkin snub-nosed monkeys remain in the wild
The Tonkin snub-nosed monkey is an incredibly rare primate, thought to have died out until some were discovered deep in the northern Vietnamese rainforests in the late 1980s.
Le Khac Quyet, a scientist who works for the Cambridge charity Fauna and Flora International (FFI), is a leading expert on the endangered primate.
He discovered a population of the monkeys, named for their distinctive up-turned noses, in 2002 and has recently made another successful trip, finding another tribe in a location thought to be barren of the creatures.
He was able to locate the monkeys after hearing that villagers had spotted animals matching the Tonkin's description. This was confirmed when the FFI showed locals video footage of the apes in action.
"When I saw the Tonkin snub-nosed monkeys, I was overjoyed," said biologist Le Khac Quyet.
The monkeys were found in a remote forest in north-western Vietnam
"This new discovery further underlines the importance of learning more about the monkeys' range and distribution.
"There is still time to save this unique species, but with 200 or so left and the threat still strong, we need to act now," he added.
The FFI team suggested that this group had associated humans with danger, perhaps as a result of ongoing threats from hunters.
The IUCN Red List of Threatened Species lists the monkeys as 'Critically Endangered' because their numbers have continued to decline as a result of intensive hunting and deforestation.
But the FFI's recent discovery has given hope that the species can re-establish itself in Vietnamese rainforests.
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