A flying snake, the pit viper is among the rare and new species found in a cave in Cambodia

Researchers have discovered many rare and new species in previously unexplored caves in Cambodia, including the flying snake and the florescent-turquoise pit viper.

The creatures were discovered during a multi-year biodiversity study that examined more than 60 limestone caves in Battambang province in western Cambodia. The project took researchers to 10 different hills across the region known as karsts, which are limestone cliffs full of hidden caves and nature, according to a report by Fauna & Flora Cambodia, an organization leading the research alongside the country’s environment ministry.

Cambodia’s karst formations have historically been among the least studied, the organization said. He described karsts as “small islands of habitation, each with its own flora and fauna,” which have become isolated over time, as human activities have grown around them.

“Since we are surrounded by a sea of ​​unpleasant man-made habitats, most of these animals are actually trapped,” said Fauna & Flora. “Today, each of those small karst areas contains species that are found nowhere else in the world.”

From November 2023 to July 2025, teams of experts entered the caves through narrow gaps in the limestone, passing through dark tunnels that were, often, large enough to crawl on hands and knees. Photos and videos show explorers lurking in jagged crevices deep in the karst, using flashlights to guide them along the pitch-black passageway of the rock cavities. In some illustrations, the bats are just flying overhead.

New and familiar types

At the front of the web of tight spaces sat an untouched series of caves, where researchers uncovered many rare species in addition to some never seen before. In addition to the pit viper, they found what the report called “leaf-toed geckos” and brightly colored millipedes, which may be poisonous.

The pit viper has yet to be officially identified, but the report called it a “spectacular new species” with distinctive triangular heads, which are “highly venomous” and which “track their warm-blooded prey using heat-sensitive pits behind their noses.”

“Each of these isolated karst areas acts as its own small laboratory – where nature conducts the same experiment over and over independently,” said Lee Grismer, a professor of biology at California’s La Sierra University who has worked on biodiversity research, in a statement. Grismer said the result of these isolated conditions is the growth of species that exist only there, sometimes within a single cave.

Lists of other species, some rare, some not, were recorded inside the caves, too.

The researchers found many reptiles, including the python, the world’s longest snake, and the blue flying snake. Also known as the ornate flying snake or golden tree snake, it is native to South and Southeast Asia.

They also encountered spotted-legged tree frogs and technicolored agamid lizards, which are commonly seen throughout the area, according to the report.

Conservation work

In addition to learning more about the mysterious ecosystem of karsts, biodiversity research was aimed at advocating for their conservation. The ecosystem is among the least protected in the world, says Fauna & Flora. The organization noted that karst habitats are “threatened by unplanned cement mining, uncontrolled tourism, wildfires, logging and hunting,” and only 1% is legally protected worldwide.

“Every time you destroy one of these hills, species may be at risk of extinction,” said Sothearen Thi, a biodiversity coordinator who also worked on the study, in a statement. Many species may disappear before they are found.