Reptiles and Amphibians of Thailand

Thailand's Snakes, Lizards, Turtles, and Frogs

Bornean Dark-necked Slug Snake

Asthenodipsas borneensis

This species is not found in Thailand
Borneo Slug-eating Snake Asthenodipsas borneensis formerly malaccanus malaysian borneo
Borneo (Christian Langner / CC BY-NC)

English name: Borenan Dark-necked Slug Snake (aka “Borneo Slug Snake”)
Scientific name: Asthenodipsas borneensis (formerly Asthenodipsas malaccanus)
Thai name:

Description: To 50cm. A small snake with a streamlined head horizontally broader than the vertically compressed body. The head is white to dark grey and is followed by a long black blotch covering both sides of the neck. Has a tan, orange, or brown body with dark crossbars on the sides. Eye is red.

Relevant scale counts: Dorsal row of scales forms keel down body’s length. 7-8 supralabial scales.

Similar Species: Malayan Slug Snake has a weak dorsal keel and and dark body with white paravertebral blotches. It is found in Sumatra, peninsular Malaysia and southern Thailand.
Smooth Slug Snake lacks the dorsal keel and striking white head.
Blunt-headed Slug Snake has a shorter, broader head, does not have the white head and black neck, and has a more slender body.

Range: The island of Borneo.

Habitat: Mature forest.

Place in the ecosystem: The Bornean Dark-necked Slug Snake and its close relative the Malayan Slug Snake are unique among slug snakes in that they appears to feed exclusively on slugs and not snails. This could be why unlike other slug snake species they shows no asymmetry in its jaw and tooth structure.

Danger to humans: This snake is no danger to humans.

Conservation status and threats: Conservation status is unknown.

Interesting facts: The Bornean Dark-necked Slug Snake was once considered the same species as the Malayan Slug Snake despite quite clear visible differences. A January 2020 paper by Quah et al. described them as distinct species for the first time.

Another new slug snake species, the Sabah Mountain Smooth Slug Snake (Asthenodipsas stuebingi), was recently described from certain highlands in Borneo. It appears similar to the Bornean Dark-necked Slug Snake except that it has a black eye, 6 supralabial scales instead of 7-8, and is found in mountainous regions (900-2000 m elevation).

References:
A taxonomic revision of Asthenodipsas malaccana with a description of a new species from Borneo
A taxonomic reappraisal of the Smooth Slug Snake Asthenodipsas laevis in Borneo with the description of two new species
Reptile Database: Asthenodipsas stuebingi

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