Ptyas nigromarginata
Ptyas nigromarginata, commonly known as the green rat snake or black-bordered rat snake, is a species of snake in the family Colubridae. The species is endemic to parts of Southeast Asia, including regions of China, India, Myanmar, and Vietnam. This slender, agile snake is characterized by its striking green coloration, often accompanied by a distinctive black border along its dorsal scales.
Geographic range
P. nigromarginata is found in Bhutan, Nepal, India, northern Bangladesh, northern Myanmar, China, and possibly northern Vietnam. The type locality is Darjeeling, India.It has been recorded from elevations between 500m to 2300m.
Description
A large snake, P. nigromarginata may attain a total length of, which includes a tail long. Dorsally, it is green, with each dorsal scale edged in black. The top of the head is brownish. In adults, there are four broad black stripes on the posterior third of the body and on the tail. In juveniles the stripes extend the full length of the body and tail. Ventrally, it is greenish white. Frank Wall, a notable herpetologist, vividly described the species:Ptyas nigromarginata has often been confused with other species, particularly Ptyas dhumnades. This misidentification is further complicated by the striking resemblance between juveniles of the two species. Both exhibit a similar black and whitish striped pattern across much of their bodies, leading to frequent errors in identification.
The secretion from the anal glands has been described as having a blackish coloration, resembling that of kraits.
Scalation
The dorsal scales are arranged in 16 to 18 rows at the midbody, reducing to 14 or 16 rows posteriorly, with the upper rows being keeled. The ventral scales range from 189 to 209, and the anal scale is divided. The subcaudal scales, numbering between 120 and 142, are paired.The head scalation includes eight supralabials, with the 4th and 5th touching the eye. A single loreal scale is present, along with one preocular and one presubocular scale. There are two postocular scales and a temporal scale arrangement of 2+2.