EDINBURGH, Scotland – Can there be more lurking in the mist? Despite a startling find announced Tuesday that doubled the estimated number of western lowland gorillas in central Africa, scientists warned that hundreds of primate species remain in danger of extinction.

A census by the Wildlife Conservation Society raised the estimate for gorillas in the Congo jungle from between 50,000 and 100,000 to around 200,000, substantially changing the picture of a great ape population thought devastated by the Ebola virus, hunting and deforestation.

While the news was well received, scientists gathered at the 22nd International Primatological Society Congress in Edinburgh warned against celebrating too soon.

“If verified, the discovery of these new populations of gorilla are hugely significant for our work as conservationists, but we must not be distracted from the very real and present danger these gorillas are in from man and Ebola,” said John Oates, emeritus professor of primatology at Hunter College in New York.

Oates said that while the news was good for the iconic great apes made famous by Dian Fossey in “Gorillas in the Mist,” many lesser known primates are in deepening peril.

A report released Tuesday by the International Union for Conservation of Nature and other groups warned that nearly half of the world's 634 species and subspecies of primates are threatened with extinction due to human activity.

The figures were particularly grim in Asia, where more than 70 percent of primates were on the union's “Red List” of vulnerable or endangered species.

“There is a danger that we concentrate on the more famous species,” Oates said. “What about the other species that we've identified as in danger? There are so many that are on the brink of extinction.”

Among them is the highland gibbon, which counts just 19 known individuals. The review warned it will be tough battle to save that Asian primate from extinction.

Simon Stuart, with Conservation International, which provided data for the review, said primate populations are shrinking in Asia due to hunting and habitat destruction – some linked to the booming biofuel industry.

“In Malaysia, Sumatra and Borneo the big problem is destruction of forests to make way for palm oil and biofuels. Ironically, with biofuels, something that is nominally associated with helping the environment can have harmful unintentional consequences,” Stuart said.

Scientists working in the region described an uphill struggle to save endangered animals.

Vicky Melfi, from the British-based Whitley Wildlife Conservation Trust, said the macaque population had plummeted on the Indonesian island of Sulawesi, where she spent three months as part of a population count.

“In 1980 the population density (of macaques) was as much as 300 individuals per square kilometer. In 10 years this had decreased to between 60 to 20 individuals per square kilometer,” she said.

“Imagine the human population of the world reduced to that of one small town. That's what we are talking about here,” Melfi added.

Oates, the New York-based primatologist, said scientists often stumble on new species, but he played down the probability of finding large new hidden primate populations such as the one identified in Congo by the Wildlife Conservation Society, which is based at the Bronx Zoo in New York.

“The habitats in which they live are largely impenetrable and we constantly find new species,” Oates said. “Having said that, this (the western lowland gorillas) remains a unique find. I don't know if we'll ever find something on this scale again.”

Jillian Miller, executive director of the Gorilla Organization, an international conservation group, wasn't so sure.

“I think the lesson for conservationists today is that, yes, the world is full of surprises. There's a lot of uncharted territory there in central Africa, there may be other populations,” she said in an interview with CNN.

But while she called the Congo find “the best news we've ever had,” Miller also warned of the threats facing primates, saying governments and conservation groups must work together to protect the animals. “We must not become complacent,” she said.

Asked how such a huge population of gorillas could go unnoticed by scientists, Miller said: “We're talking about the Congo Basin rainforest here. It is vast, it is huge, it's second only to the Amazon. And it's impenetrable.”