Reptiles and Amphibians of Thailand

Thailand's Snakes, Lizards, Turtles, and Frogs

Smooth Slug Snake

Asthenodipsas laevis

This species is found in Thailand, but not within Bangkok itself
Smooth Slug Snake Asthenodipsas laevis Pareas malaysia
Smooth Slug Snake in peninsular Malaysia (© Evan Quah)

English name: Smooth Slug Snake
Scientific name: Asthenodipsas laevis
Thai name: งูกินทากเกล็ดเรียบ (Ngu Gin Thaag Gled Riab)

Description: To 55 cm. Its long slender body is vertically compressed and brown, reddish-brown, or grayish-brown with black bands. Lighter orange or yellowish scales on the top of the body can form a light dorsal line. The head is the same color as the body, small and distinct from the neck with a blunt nose.

Relevant scale counts: 6 supralabial scales. As the name implies, the scales are smooth and there are no keels on the dorsal ridge.

Similar Species: Malayan Slug Snake has a striking white head followed by an extensive black blotch on the neck and 7-8 supralabial scales.
Keeled Slug Snake has a more distinct head, keels on the dorsal scales, no dorsal line, and is typically lighter and more uniform in color.
Blunt-headed Slug Snake has a shorter and deeper head along with a more slender body and a unique vertical eyestripe.
Siamese Cat Snake, Dog-toothed Cat Snake, White-spotted Cat Snake, and Jasper Cat Snake are all much longer with a more distinct head and lack the vertebral stripe.

Range: Southern Thailand, Malaysia, Singapore and Indonesia.

Habitat: Mature forest.

Place in the ecosystem: Like most other slug snakes it feeds primarily on snails, as well as slugs at times. It may be eaten by larger snakes, nocturnal birds and carnivorous mammals such as civets.

Danger to humans: The Smooth Slug Snake is no danger to humans.

Conservation status and threats: This species is rarely found on the mainland portion of its range and known localities are widely spaced, though it is more common in Borneo and other islands in Indonesia. Few records have ever been found in Thailand.

Interesting facts: Slug snakes have a specialized hook-like jaw with more teeth on the right-hand side than on the left. This rare “non-symmetric” feature came about because the snails they prey on tend to have right-handed twisting shells, therefore making it easier for the snake to get the right side of its mouth into the shell than the left side. In fact, studies have shown that the snakes are far more successful at extracting snails out of those right-handed shells than they are when faced with a snail in a left-handed twisting shell.

A new slug snake species, Asthenodipsas jamilinaisi, was recently described from certain highlands in Borneo. It appears similar to the darker versions of the Smooth Slug Snake except that it has a clear keel along the vertebral scale row along with some other scale differences, and is found in mountainous regions (900-2000 m elevation) rather than the lowlands (sea level to 1000 m) favored by the Smooth Slug Snake.

Below is one possible example of the new species (Asthenodipsas cf.  jamilinaisi).

Asthenodipsas cf.  jamilinaisi borneo malaysia
Asthenodipsas cf. jamilinaisi in Borneo (© Chien C. Lee)

References:
Reptile Database: Asthenodipsas laevis
Ecology Asia: Smooth Slug Snake
Asymmetrical Snakes
A taxonomic reappraisal of the Smooth Slug Snake Asthenodipsas laevis
Serpents of Thailand

%d bloggers like this: