Colubridae-2-D-G-Check list snakes northern Thailand

Colubridae-2-D-G-Check list snakes northern Thailand: snake species in the genera Dendrelaphis, Dinodon, Dryocalamus, Dryophiops, Gongylosoma and Gonyosoma.

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Dendrelaphis cyanochloris, the Blue Bronzeback (pictures above). Slender snake with conspicuous broad black postocular streak that peters out on the neck. When the anterior part of the body is expanded a multitude of bright glitters are seen (the edges of the dorsal scales) often forming vague oblique reticulations. The upper side of the head and the dorsum is brown to copper brown, the belly pale green (pale yellow anteriorly, as the chin and throat)). It is rather common in most of northern Thailand’s forests at elevations of 700-1400 m asl. A. Head of juvenile from Umphang District, Tak. B. Adult from Pang Sila Thong District, Kamphaeng Phet. C. Belly shown by DOR from Doi Inthanon, Mae Chaem District, Chiang Mai. D. Upper side head of adult from Pai District, Mae Hong Son. E. Juvenile from Phu Hin Rong Kla National Park, Nakhon Thai District, Phitsanulok.

Dendrelaphis ngansonensis, the Vietnamese Bronzeback (pictures above). This bronzeback is very similar to D. cyanochloris, but it can be told apart  by its cream belly (pale green in D. cyanochloris). What’s more, the first row of dorsals is cream like the belly (bronze-brown in D. cyanochloris) (see D). This bronzeback can easily reach a length of 150 cm, and is therefore much larger than D. cyaonochloris (max. lenght 133 cm). It is known from the Central Thailand (Chanthaburi, Nakhon Nayok) and Northeast Thailand (Nakhon Ratchasima, Chaiyaphum), but I also came across it in Nam Nao District, Phetchabun, in the northern region. A-D. All pictures are of the same road-killed subadult from the Khao Yai National Park (Mueang District, Nakhon Nayok).

Dendrelaphis nigroserratus or Saw-tooth-necked Bronzeback (pictures above). This species was first described in 2012. Its meristics are similar to D. cyanochloris but it grows larger in size (the largest specimen thus far recorded was 163 cm). The conspicuous black saw-tooth pattern on the neck easily tells it apart from the other bronzeback species. The upper side of the head is greenish bronze (not brown as in D. cyanochloris). In northern Thailand it is recorded only in the southern part of Tak Province (Umphang and Phop Phra Districts) where it lives in forests at elevation of 800-1300 m asl., often hiding in bamboo clubs. A. Subadult from Umphang District, Tak. B. Juvenile from Umphang District, Tak. C. Head of an adult from Phop Phra District , Tak. D. Adult from Kaeng Krachan National Park, Kaeng Krachan District, Phetchaburi (Central Thailand).

Dendrelaphis pictus, the Common Bronzeback (pictures above). The upper side of this slender snake (maximal length 130 cm) is bronze, the belly whitish or pale yellow. The head is copper brown. It can be told apart from the other bronzeback species in Thailand by a distinct black ventrolateral stripe that runs over the corners of the ventral shields (B). When the snake expanses the anterior part of the body, the glittering, bright blue edges of the scales are shown (D, F). It is a very common snake throughout Thailand, including the northern region. It is a diurnal species, most often encountered in deciduous forest, plantations and gardens at low elevations (100-600 m asl). A. An adult from Mae On District, Chiang Mai. B. View of flanks and belly of a road-killed specimen from Lampang’s Mueang District, showing the black ventrolateral stripe (blue arrow) and the ventral keels (red arrow). C, F. Individual from Lampang Province. D. Juvenile from Chiang Mai’s Mae On District. E. An adult from Phayao’s Mueang District.

Dendrelaphis subocularis or the Subocular Bronzeback. This bronzeback is also known as Mountain Bronzeback, a bit misleading name, at least in no