Scientists have identified more than 200 new species in the Greater Mekong region of south-east Asia, a report by conservation group WWF says.
They say that throughout 2010 more than 100 plants, 28 reptiles, 25 fish and seven amphibians were discovered.
But the WWF warns that many are endangered - while others could disappear before they are identified.
The Greater Mekong area includes Thailand, Cambodia, Burma, Vietnam, Laos and Yunnan province of China.
It is one of the world's most bio-diverse areas, home to some of the planet's most endangered wild species including the tiger, the Asian elephant and the Mekong dolphin.
The WWF says that more than 1,000 species have been discovered in the Greater Mekong over the past 10 years.
BBC environment reporter Mark Kinver says that new species are frequently found in the region because of increasing levels of human activity, which is proving to be a double-edged sword.
On the one hand, building roads opens up remote habitats to scientists who can then venture into previously unexplored areas and record the rich diversity of wildlife.
But this can also have a damaging ecological impact, especially if it results in a greater exploitation of the land which destroys these fragile ecosystems, our correspondent adds.
Among recent finds was a female-only lizard species, which reproduces by cloning, and was only discovered after a scientist spotted it on the menu of a Vietnamese restaurant.
Ms Bladen said that the female-only cloning lizard was also an exiting find.
"This lizard is not genetically diverse and is therefore very vulnerable. So these species are often found in shrinking habitats that are under pressure from rapid and unsustainable development and climate change," she said.
"But while we have extraordinary richness in this region, it is a richness that is under threat and shrinking fast and needs urgent effort to protect it."
The latest WWF report comes just days after the organisation announced the extinction of the Javan rhino in Vietnam because of poaching, and a 70% reduction in the number of wild tigers in just over 10 years.
China, Laos, Thailand and Cambodia are all planning hydropower dams along the Mekong river to meet the increasing demand for electricity.
Another new species - discovered in 2010 - is a snub-nosed monkey found in a remote and mountainous part of Burma's Kachin state, WWF spokeswoman Sarah Bladen told the BBC.
"It is well known to locals, who would spot the black-and-white monkey in the rain with its head between its knees, shielding it from the rain running into its upturned nose," she said.