This species is found in Thailand, but not within Bangkok itself
English name: White-lipped Keelback
Scientific name: Hebius leucomystax (formerly Amphiesma leucomystax)
Thai name: งูลายสาบท้องสามขีด (Ngu Lai-saap Thong Saam Khid)
Description: To 77cm (males are longer and slimmer than females). Dark grey with two very faint dorsolateral stripes marked distinctly by rows of jagged rust-colored spots. Has an uninterrupted broad white stripe on the upper lip which continues on to the neck before turning beige and coming together as a “V”. Venter is white to cream with faint indistinct greyish-brown blotches on the edges of the scale.
Relevant scale counts: 19 midbody scale rows, rows 3-17 are keeled while the first two rows on each side are smooth. 154-168 ventral scales and 99-103 subcaudals. Two internasals are narrowed near the front.
Similar Species: Tai-Yong Keelback has a narrower white stripe which starts at the eye and does not continue to form a “V” on the neck, 139–156 ventral scales, and more-or-less distinct dorsolateral stripes.
Khasi Hills Keelback has a narrower white lip with dark scale margins rather than continuous stripe, 141-153 ventral scales and 105-108 subcaudals, and distinctly keeled first two scale rows.
Deschauensee’s Keelback has a narrower dirty white or tan lip and initial eyestripe, belly typically covered in multiple rows of dots, and 115-141 subcaudals.
Range: Central Vietnam, northern Cambodia, Laos, and northern/eastern Thailand.
Habitat: Near forest streams in evergreen monsoon forest from 100-1500m elevation, typically on hill/mountain slopes though not always.
Place in the ecosystem: Likely feeds primarily on frogs. Would be eaten by larger snakes, civets, and birds of prey.
Danger to humans: Is a rear-fanged snake but is not known to be dangerous to people.
Conservation status and threats: This species may be threatened by logging and the conversion of its habitat to agriculture, but populations in Vietnam and Laos are believed for now to be generally secure. It has very rarely been observed in Thailand.
Interesting facts: The White-lipped Keelback was first described in 2007 based on specimens found in Vietnam. There was a suggestion that it may occur in Thailand, but its presence in the country wasn’t confirmed until 2015 when Oliver Pauwels et al. found an old mislabeled specimen from Roi Et Province in the Thailand Natural History Museum. No live Thai specimen has ever been confirmed. Recently a nature tour came across a possible example of the species in Phayao Province, but as they could only see the head it’s hard to know for sure if they found the same species or a new one!
IUCN Red List: Hebius leucomystax
A new species of the natricine snake genus Amphiesma from the Indochinese Region
First confirmed record of the stream-dwelling snake Amphiesma leucomystax
A Field Guide to the Reptiles of Southeast Asia