New Species of Venomous Pit Viper Discovered In MyanmarTrimeresurus ayeyarwadyensis. Photo by Don Lin/Zookeys

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New Species of Venomous Pit Viper Discovered In Myanmar

The genomic data placed T. ayeyarwadyensis as a new sister species to T. erythrurus.

Trimeresurus ayeyarwadyensis was found to occur in the Yangon region's Hlawga Park and Pyapon and Myaungmya districts of Myanmar.

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Researchers looking at genomic data from pit vipers of the Trimeresurus erythrurus–purpureomaculatus complex are a distinct species based on ” robust population genetic and species delimitation analyses.” Based off their new data, the new species Trimeresurus ayeyarwadyensis sp. nov. shares morphological characteristics with T. erythrurus and T. purpureomaculatus and are closely related.

The researchers determined that some specimens of Trimeresurus ayeyarwadyensis vary in the blotches of color on their green dorsal coloration. While some have dark dorsal blotches, others of the same species are absent any distinct dorsal blotches. Those specimens with dark dorsal blotches share the same blotched trait with T. purpureomaculatus but not T. erythrurus.

Trimeresurus ayeyarwadyensis

Trimeresurus species in Myanmar A T. ayeyarwadyensis sp. nov. (CAS 213410) from Hlawga Wildlife Park, Yangon Region (photo by CAS-Myanmar Herpetology Survey team, CAS-MHS) B T. erythrurus (CAS 235958) from Phalum District, Chin State (photo by Hla tun) C T. ayeyarwadyensis sp. nov. (CAS 219764) from Meinmahla Kyun Wildlife Sanctuary, Pyapon District, Ayeyarwady Region (photo by Hla tun) D T. ayeyarwadyensis sp. nov. (CAS 212245) from Mwe Hauk Village, Ayeyarwady Region (photo by Dong Lin).

The researchers studied both anesthetized live specimens and specimens found in collections at the California Academy of Sciences (CAS), University of Florida (UF), Naturhistorisches Museum Wien (NMW), Museum of Comparative Zoology, Harvard University (MCZ), and the Natural History Museum London (NHMUK/BMNH). A genomic study into the population genetics of the complex found that gene flow was present between the snakes, with less gene flow occurring in T. purpureomaculatus. The genomic data placed T. ayeyarwadyensis as a new sister species to T. erythrurus.


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Trimeresurus ayeyarwadyensis was found to occur in the Yangon region’s Hlawga Park and Pyapon and Myaungmya districts of Myanmar. The venomous snake female holotype had a total length of 1008.3 mm with a snout to vent length of 935 mm. It is green in coloration with indistinct dark dorsal markings and a distinct pale dorsolateral stripe. This stripe covers 90 percent of the first scale row, the study says. The stripe also extends to the second scale row.

The complete paper, A new species of pit-viper from the Ayeyarwady and Yangon regions in Myanmar (Viperidae, Trimeresurus) can be read on the Zookey’s website.