Colubridae-5-P-S-Check list snakes northern Thailand


Colubridae-5-P-S. For the Illustrated Check List of the Colubrid snakes in the genera Plagiopholis, Psammophis, Ptyas and Sibynophis click here .

Plagiopholis nuchalis, the Arrow-head Snake or Assamese Mountain Snake (above). A little sturdy-built snake widespread in mountain forests of northern Thailand. The upper side is ochre, dark brown or reddish-brown, the belly whitish or speckled grey with black rectangular blotches. The black neck mark looks like an arrow-head, but it is sometimes reduced to a little black streak. A. Adult from Doi Inthanon, Chomthong District, Chiang Mai. B. Same specimen as in A, showing head scalation. C. Adult in defensive posture, Mae Taeng District, Chiang Mai. D. Subadult from Mueang District, Chiang Mai showing the pattern of the belly. E-F. Adult from Mae Taeng District, Chiang Mai (in E eating earth worm).

Plagiopholis blakewayi (no picture). This snake resembles P. nuchalis but its head scalation is different. In Thailand it has only been reported from Doi Pha Hom Pok, Fang District, Chiang Mai, in the very north of the region where it occurs at high elevations.

Psammophis indochinensis or Indo-Chinese Sand Snake (above). This snake in many respects resembles a Colubrid snake, but is usually accommodated within the family of Lamprophiidae. The snake reaches a length of more than 1 m. Scales are smooth. It has a very characteristic pattern of stripes (see 3 examples of skins at midbody, above). In northern Thailand I came across this species in Chiang Mai, Uthai Thani and Sukhothai provinces (and beyond the North also in Chaiyaphum and Samut Songkhram provinces). All records were in the period 2001-2004. In those years, several specimens were found in the lowlands of San Kamphaeng and Mae On districts east of Chiang Mai City. With the exception of a record in Mae On District in 2011, I did not come across the species anymore, despite intensive surveying. However, a picture of this snake from Nakhon Sawan Province was posted on a website in 2016. Possibly population densities in Thailand have drastically declined. A. A picture of the species adapted from Nutphand (2001). B. Skins of specimens from various parts of northern Thailand.

Ptyas carinata, the Keeled Rat Snake.
Ptyas korros, the Indo-Chinese Rat Snake, is a brown snake that can reach a length of 200 cm. It has large black eyes with a round pupil. The belly is light yellow. It is a common snake throughout the region, in particular in cultivated areas. A. An adult specimen from Mueang District, Tak. B. A juvenile from Wabg Nuea District, Lampang. C. A subadult from Mueang District, Chiang Mai. D. An adult from Mueang, Chiang Mai. E. Head of an adult from Thung Hua Chang District, Lamphun. F. Head and neck of Ptyas korros (below) compared to P. mucosa (above), Mae Rim Snake Farm, Chiang Mai.

Ptyas mucosa, the Common Rat Snake, is a large snake that can reach a length of 250 cm. The ground color is pale brown with black bands posteriorly. The black eyes are large. The supralabials have distinct black edges. This snake occurs throughout the region, in particular in cultivated areas, such as corn and sugar cane fields, but it is usually less common than the Indo-Chinese Rat Snake. A-B. Subdult from Phrao District, Chiang Mai. C. Head of an adult from Nong Bua District, Nakhon Sawan. D. A juvenile from Mueang District, Tak.  E. Mae Rim Snake Farm, Chiang Mai. F. Posterior part and tail of an adult from Wang Nuea District, Lampang, showing the black crossbars.
Ptyas nigromarginata, the Green Rat Snake. Large snake up to 300 cm. Adults with brown head, white chin and yellow throat. Anteriorly green (C), posteriorly striped black-and-white. Juveniles striped black-and-pale green throughout (A-B) with yellowish-brown head. A rare snake only known from submontane forest in the mountains of Nan Province. A-B. A juvenile from Bo Kluea District, Nan. C. An adult from Pua District, Nan. More about this snake: click here or download   Vogel & Hauser, 2013-Addition of Ptyas nigromarginata to the Snake Fauna of Thailand  (PDF 4.5 megabite).
Sibynophis collaris, the Common Blackhead. Slender brown snake with long tail that reaches a length of 70 cm. The upper side of the head is black, edged at the neck with an orange line. Supralabials partly white. Body brown, in the middle with a reddish hue. Row of black dots on the vertebral row of dorsal scales. Quite common in forests at elevatios of 800-1500m asl. A-B. Specimen from the Phu Hin National Park, Nakhon Thai District, Phitsanulok. More about the Common Blackhead: click here .