Reptiles and Amphibians of Thailand

Thailand's Snakes, Lizards, Turtles, and Frogs

Sawtooth-necked Bronzeback

Dendrelaphis nigroserratus

This snake is found in Thailand but not in Bangkok
Dendrelaphis nigroserratus Sawtooth-necked bronzeback thailand Kaeng Krachan
Sawtooth-necked Bronzeback in Kaeng Krachen National Park (Thai National Parks / CC BY-SA)

English name: Sawtooth-necked Bronzeback
Scientific name: Dendrelaphis nigroserratus
Thai name: งูสายม่านงูสายม่าน คอดอกเลื่อยสีดำ (Ngu Sai Maan Khod Dok Lueai See Dam)

Description: To 163cm long, quite large for a Bronzeback. Body is olive-brown turning greenish-bronze on the neck and head, with pale yellow or lime bands appearing regularly on the forward half of the body. An especially thick black eyestripe broadens on the neck and then breaks gradually into bars, creating the “sawtooth” pattern that gives the snake its name. There is a yellowish tint to the neck, though when threatened the body expands and blue skin between the scales appears. Belly is yellow to grayish-green.

Relevant scale counts: 15 rows of midbody scales with enlarged vertebral scales. 197–204 ventrals and 148–152 subcaudals.

Similar Species: Banded Bronzeback is smaller, has a more immediate transition from eyestripe to bands without the distinct “sawtooth” effect, and has 149-167 ventrals and 120-145 subcaudals.
Blue Bronzeback is smaller, is clearly deep blue on the neck without the yellow, and lacks the sawtooth pattern on the neck.
Painted Bronzeback is less robust, lacks the sawtooth pattern, and has a distinct dorsolateral stripe.

Range: Western Thailand and southeastern Myanmar.

Habitat: Hill forest from 800-1350m, often near streams or in bamboo thickets.

Contribution to the ecosystem: Known to feed on frogs, likely lizards as well. Would be eaten by birds of prey and larger snakes.

Danger to humans: This species is not dangerous to humans.

Conservation status and threats: Appears to be vulnerable to deforestation and is now only found within protected areas, though it is common where found.

Interesting facts: The Sawtooth-necked Bronzeback was only named as a distinct species in 2012. It went unnoticed until then in part due to its similarities to the Blue Bronzeback and because its range is in the isolated border regions of Thailand and Myanmar. Gernot Vogel and Johan van Rooijen had noticed a couple specimens with unusual size and strange neck coloration in museums, but it was not until Sjon Hauser uncovered fresh specimens in Tak in 2011 that the snake could be described as a new species.

The border areas of Thailand on all sides are among its least explored regions. Over the last ten years a number of Thai herpetologists and ex-pats with strong snake knowledge have begun exploring these isolated regions with more intensity, resulting in a flurry of newly discovered species for the country. It is interesting that snakes are often among the last major vertebrates to be fully surveyed in a region. This is often due to their subterranean and/or nocturnal habits, but even arboreal, diurnal species like the Sawtooth-necked Bronzeback aren’t necessarily found right away. This could be because their higher position on the food chain causes them to live in lower population densities than most frogs, lizards, and birds.

Dendrelaphis nigroserratus, the Sawtooth-necked Bronzeback
A new species of Dendrelaphis from Thailand and Myanmar
Ecology Asia: Sawtooth-necked Bronzeback
Thai National Parks: Sawtooth-necked Bronzeback
IUCN: Sawtooth-necked Bronzeback

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