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New species of pit viper discovered in Myanmar

A new species of pit viper from Myanmar has been identified and described. The study was led by herpetologist Dr. Chan Kin Onn, formerly of the Lee Kong Chian Natural History Museum, Singapore, and now with the University of Kansas Biodiversity Institute and Natural History Museum.

The discovery showcases the complexity and challenges in classifying species, particularly when encountering both cryptic species and highly variable individual species simultaneously.

Asian pit vipers 

Dr. Chan’s study focuses on the Asian pit vipers of the genus Trimeresurus, known for their wide range of morphological variation. 

This genus includes species that are difficult to distinguish due to their similar appearance, as well as species that exhibit significant variation yet belong to the same species. The study highlights a particular pit viper in Myanmar that embodies this dual challenge.

Hybrid species 

The newly discovered Ayeyarwady pit viper (Trimeresurus ayeyarwadyensis) is named after the Ayeyarwady River in Myanmar and presents an intriguing blend of characteristics from its sister species. 

The redtail pit viper (Trimeresurus erythrurus), found along Myanmar’s northern coast, is typically green with no markings. 

In contrast, the southern mangrove pit viper (Trimeresurus purpureomaculatus) is known for its distinct dorsal blotches and variable coloration, but it never appears green.

Ayeyarwady pit viper

In central Myanmar, researchers found a unique population of pit vipers that seemed to combine features of both the redtail and mangrove pit vipers. Initially believed to be a hybrid population, genomic analysis by Dr. Chan revealed that this group was, in fact, a distinct species.

Adding to the intrigue, the Ayeyarwady pit viper displays considerable variability within its own populations. Some exhibit dark green colors with distinct blotches, easily distinguishable from the bright green, unmarked redtail pit viper. However, other populations of the Ayeyarwady pit viper closely resemble the redtail pit viper, being bright green with no blotches.

Significance of the discovery

Dr. Chan explained the significance of this finding: “This is an interesting phenomenon, where one species is simultaneously similar and different from its closest relative (the redtail pit viper). We think that at some point in the past, the new species may have exchanged genes with the redtail pit viper from the north and the mangrove pit viper from the south.”

The discovery of the Ayeyarwady pit viper not only adds to the biodiversity of the region but also provides valuable insights into the evolutionary history and complexity of species differentiation. This research underscores the dynamic nature of species classification and the ongoing efforts to understand the rich tapestry of life on Earth.

More about pit vipers

Pit vipers are a family of venomous snakes known scientifically as Crotalinae. They are characterized by a distinctive heat-sensing pit organ located between the eye and the nostril on each side of their head, which aids them in detecting warm-blooded prey even in the dark. This feature sets them apart from other types of snakes.


These snakes are found primarily in the Americas and Asia. They vary greatly in size, from the relatively small hognose pit viper, which can be less than a foot long, to the large bushmasters, which can exceed 10 feet in length.


Pit vipers are known for their potent venom, which they use to immobilize and pre-digest their prey, which is typically small mammals, birds, and other reptiles. The venom composition varies among species and can cause significant tissue damage and disruption of blood clotting in the victims.


The appearance of pit vipers is diverse. Many species have a robust and stocky build, and they often exhibit striking patterns and colors that help them blend into their natural environments. This camouflage is a key aspect of their hunting strategy, allowing them to lie in wait for unsuspecting prey.


Reproduction among pit vipers varies, with some species laying eggs (oviparous) and others giving birth to live young (viviparous). In species that give birth to live young, the embryos are nourished in the mother’s body.

Ecological role

Pit vipers play an important role in their ecosystems as both predators and prey. They help control the populations of their prey species and are, in turn, preyed upon by larger animals, including birds of prey and mammals.

Despite their fearsome reputation, pit vipers are generally shy and avoid humans. However, they will defend themselves if threatened or stepped on, making them a significant source of snakebite injuries in their native regions. Their venom has also been a subject of medical research, contributing to the development of new drugs and antivenoms.

The study is published in the journal ZooKeys.

Image Credit: Wolfgang Wüster

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