New Ayeyarwady Pit Viper Species Identified in Myanmar Following Decades of Morphological Confusion

Genetic testing reveals the Ayeyarwady pit viper is a distinct species, solving a mystery where the snake appeared to mimic multiple other species at once.

By: AXL Media

Published: Apr 22, 2026, 6:55 AM EDT

Source: Information for this report was sourced from Pensoft Publishers

Genetic Analysis Resolves a Taxonomic Puzzle

A international team of herpetologists has successfully identified a new species of venomous snake, the Ayeyarwady pit viper (Trimeresurus ayeyarwadyensis), in the river basins of central Myanmar. Led by Dr. Chan Kin Onn, researchers initially struggled to categorize the population, as its physical appearance seemed to blend the traits of two other known vipers. While morphological evidence suggested the snakes might be hybrids, advanced genomic studies confirmed that they represent a unique evolutionary branch, highlighting the complexities of identifying "cryptic" species that look nearly identical to their relatives.

A Convergence of Morphological Variation

The genus Trimeresurus is notorious among scientists for its extreme physical diversity, making traditional visual identification unreliable. In northern Myanmar, the redtail pit viper remains consistently bright green, while the mangrove pit viper in the south displays dark blotches on gray, brown, or yellow scales. The newly discovered Ayeyarwady species sits geographically between these two, displaying a baffling range of appearances that include both dark-blotched green scales and entirely unmarked bright green bodies. This overlap often makes certain populations of the new species indistinguishable from the redtail pit viper to the naked eye.

The Role of Ancestral Gene Flow

The "baffling" nature of the Ayeyarwady pit viper’s appearance is likely the result of historical gene exchange. Researchers theorize that at various points in the past, this species may have interbred with both the redtail pit viper to the north and the mangrove pit viper to the south. This gene flow accounts for the presence of blotched patterns usually seen in southern species appearing on the green bodies typical of northern populations. The 2023 genomic study used to define the species accounted for this gene flow, proving that despite these shared traits, the population has remained a distinct lineage.