How to Identify the Keeled Rat Snake (Identification Guide)

Key identifying features

The keeled ratsnake (Ptyas carinata) is a large, robust colubrid best recognized by its heavily keeled dorsal scales, which give the body a rough, ridged texture distinct from the smoother-scaled ratsnakes in the same region. It is one of the larger non-venomous snakes found in its native forests.

Coloration & pattern

Ground color is typically olive-brown, grayish-brown, or yellowish-tan, often with faint darker crossbands or mottling that can be subtle on the anterior body and slightly more visible toward the tail. Some individuals show a more uniform coloration with little obvious patterning. The belly is pale yellow to cream, sometimes with darker mottling along the edges.

Head, eyes & scales

The head is elongated and moderately distinct from the neck, with large eyes and round pupils. The defining feature of this species is its strongly keeled scales across most of the body, creating a raised ridge along each scale that is visible and palpable, unlike the smoother-scaled ratsnakes it can be confused with.

Size & body shape

This is a large, heavy-bodied ratsnake, with adults commonly reaching 2 meters or more, making it one of the larger colubrids within its range. The body is thick and muscular relative to more slender regional ratsnakes, with a long tail.

Range & habitat where you'll see it

The keeled ratsnake is found across Peninsular Malaysia, Sumatra, Borneo, and parts of Thailand, inhabiting lowland and hill forest, often near streams and rivers. It is a strong swimmer and climber, active by day, and preys on rodents, birds, amphibians, and other small vertebrates.

How to tell it apart from look-alikes

The strongly keeled scales are the single most reliable identification feature, easily distinguishing this species from smoother-scaled ratsnakes like the Indo-Chinese ratsnake or common trinket snake. Its larger overall size and heavier build compared to most sympatric colubrids also aid identification. Round pupils and a narrow, elongated head separate it from venomous pit vipers, which have vertical pupils and a broad triangular head.