Reptiles and Amphibians of Thailand

Thailand's Snakes, Lizards, Turtles, and Frogs

Yunnan Water Snake

Sinonatrix yunnanensis

This species is found in Thailand, but not within Bangkok itself
Yunnan Water Snake Keelback Sinonatrix yunnanensis งูลายสอจีนลายวงแหวน Lampang Thailand
Yunnan Water Snake in Lampang (© Sjon Hauser)

English name: Yunnan Water Snake (aka: “Yunnan Keelback”)
Scientific name: Sinonatrix yunnanensis
Thai name: งูลายสอจีนลายวงแหวน (Ngu Lai Sor Jiin Lai Wong Waen)

Description: To over 1m in length. A brown to greyish-olive snake with distinct black X-markings on the side filled in with beige. The X-marks connect at the top. Belly is beige with significant intrusion of the black marks.

Relevant scale counts: 19 midbody scale rows. Scales are keeled except for the first two rows on each side.

Similar Species: Angel’s Stream Snake has indistinct inverted “V” shapes on the sides. Scales are not keeled.
Boomsong’s Stream Snake lacks the distinct X markings on the sides.

Range: Southern China, northern Vietnam, and northern Thailand.

Habitat: Found near streams in montane forest up to 1200m in elevation, usually in water but sometimes in trees. Also found in agricultural and village land so long as there are streams accessible.

Place in the ecosystem: Feeds on fish and perhaps other small aquatic creatures. Would be eaten by larger snakes and monitors.

Danger to humans: Is a rear-fanged snake but its venom properties and potential danger are unknown.

Conservation status and threats: It does not appear common in the wild but there are no known threats.

Interesting facts: A Yunnan Water Snake from Chiang Rai was captured at night as it swam in the water and taken to the Queen Saovabha Memorial Institute. During the two months it lived there it fed on small fish and never left the water.

References:
First record of the Yunnan Keelback from Thailand
Review of the genus Sinonatrix in Vietnam with a new country record of Sinonatrix yunnanensis
IUCN Red List: Yunnan Keelback Water Snake
Thai National Parks: Yunnan Water Snake

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