Viperidae-Check list snakes northern Thailand

Calloselasma rhodostoma, the Malayan Pit-viper. This brown snake with triangle-shaped blotches can reach a length of about 100 cm. It occurs in most parts of the region, and is locally common in deciduous forest. The pictures above show an individual from Doi Suthep National Park, Mueang Chiang Mai (pictures©Sjon Hauser).

Daboia siamensis, the Siamese or Eastern Russell’s Viper. The ground color of this large, sturdy viper (maximal 140 cm) is buff, densely packed with brown, ovoid blotches. It is rare in northern Thailand, but has been reported in Uthai Thani and Nakhon Sawan Province. It is locally common in Central Thailand. e.g. in parts of Lopburi and Sa Kaeo Province. It is most often encountered in relatively open lowland terrains, such as mosaics of paddies, wastelands, marches and plantations. A. A captive specimen in the Mae Rim Snake Farm, Chiang Mai (the true origin of this snake was unknown). B. Pattern on flanks and belly of a road-killed specimen from Watthana Nakhon District, Sa Kaeo. C. Dorsal skin of a road-killed specimen from Sa Kaeo Province. D-F. An individual from Watthana Nakhon District, Sa Kaeo (Central Thailand). More about this viper: click here .

Ovophis monticola, the Mountain Pit-viper. This sturdy-built pit-viper reaches a length of almost one meter. The ground color is buff with rows of squarish or ameboid dark blotches that are often fused (A-C). Except for the most lateral rows, the scales in the dorsal rows are usually distinctly keeled (A). The upper side of the head is covered with tiny dark brown scales. A pale streak extends from the tip of the snout, through the eye to the end of the jaw (A-B). The white belly is mottled with brown squarish blotches (E). The upper side of the tail is adorned with a number of white ovoid spots (F). 3-4 large spines arise from the apex of the hemipenes (E). This snake is widespread in the region in evergreen forest above 1000 m. B. shows a juvenile from Khun Yuam District, Mae Hong Son, and F. the tail of a specimen from  Pua District, Nan. All other pictures show characteristics of an adult male from Doi Inthanon, Mae Wang District. Chiang Mai.

• Protobothrops mucrosquamatus, the Brown-blotched Pit-viper. This slender brown pit-viper has recently (mid-2017) been discovered in deciduous forest in Nan’s Ban Luang District. The coloration and dorsal pattern somewhat resembles Ovophis monticola (see above), but the body of the Protobothrops is much more slender. P. mucroquamatus is well-known from central and southern China and also occurs in Myanmar and Vietnam. In Thailand it is known from only one specimen. A. Adapted from a picture of a Chinese specimen. B. The head, adapted from a drawing. More about this species in Thailand in click here for pdf .
Protobothrops spec. (“Protobothrops scholaris“). From western North Thailand a species of pit-viper is known that resembles P. mucrosquamatus (see above) but it is even more slender. It is probably a new species that has not yet been described, though it has been known from Tha Song Yang District in Tak Province since 2004. Recently, specimens were collected in Omkoi District, Chiang Mai Province, and a detailed description of this species is expected in the near future (see also:  ). The picture on the left is of the sealed skin of head and neck of a road-killed specimen from Tha Song Yang District that was found amidst evergreen forest at an elevation 0f about 800 m. The dark blotch below the eye and similar blotches on the lower lip are uncommon in P. mucrosquamatus; these characteristics in combination with the high number of ventral shields and the low number of dorsal scale rows of the posterior part of the body suggest that it is a new, not yet described species of pit-viper.

Trimeresurus albolaris, the White-lipped Pit-viper. A common pit-viper in Thailand that can reach a length of one meter. The body is grass green, the belly yellowish-green. The head is very distinct from the narrow neck (B). The green upper side of the head is distinct from the yellowish parts below an imaginary line from the tip of the snout to below the eye to the end of the upper jaw. The upper side of the tail is covered with a reddish or brown streak that is not mottled (E). The eyes of both sexes are brownish-yellow with a vertically elliptic pupil (D). Males have a narrow white ventrolateral stripe, sometimes edged with grey. In females such a stripe is absent. This is the common form of the species in Central Thailand and the southern provinces of the northern region. A-B: A male from Kaeng Krachan National Park, Phetchaburi Province (Central Thailand). C-E. A female from Tha Song Yang District, Tak.

Trimeresurus cf albolabris (red-eyed “form”). In the upper part of the northern region both sexes have usually red eyes. This is possibly a color morph of the species described above, but it might also be a cryptic (new) species. It is common in (rather open) deciduous forest at moderate elevations (300-900 m).
A-C: specimens from Santisuk and Bo Kluea districts in Nan. D-E. A female from Tha Song Yang District, Tak. F-H. Adult male from Doi Inthanon, Chom Thong District. I. Juvenile from Pua District, Nan.

Trimeresurus gumprechti or Gümprecht’s Pit-viper. This pit-viper is similar to Pope’s Pit-viper (see below), but he females have bright yellow eyes. It is distributed in mountain forest in the eastern part of North Thailand and in Loei Province in the northeastern region. A-D.  An adult female from Bo Kluea District, Nan. E. An adult male from Pua District, Nan.

Trimeresurus macrops, the Big-eyed Pit-viper. This green pit-viper resembles T. albolabris (see above) but it is told apart by its large golden-yellow eyes (B, C, E) and a number of minor differences. The ground color is often bluish green (B, E). It can reach a length of almost one meter. The males have a whitish or pale bluish ventrolateral stripe (A, D, E). I never came across this snake in northern Thailand, but it is supposed to occur there. The origin of a specimen seen in Chiang Mai Zoo (D) was unknown. A-B. A male from Pak Chong District, Nakhon Ratchasima specimen. C. A bright green specimen from Pak Chong District, Nakhon Ratchasima. D. A captive specimen in Mueang, Chiang Mai. E. A bluish-green male from Ko Chang, Trat Province, but this snake may actually belong to the “new” species T. cardamonensis, known from Cambodia and Chanthaburi Province in eastern Central Thailand.

Trimeresurus popeiorum or Pope’s Pit-viper (above). In this green pit-viper both sexes have red eyes. The males have a red-and-white postocular streak and a white-and-red lateral line on the most lateral dorsal row (A, G, H). Females have a rather indistinct white lateral stripe and a psotocular streak is lacking completely (D). The scales are moderately keeled (F).  Some specimens have a row of widely spaced white dots on the vertebral row (E). The belly is green (A, G). The upper side of the tail is mottled with reddish-brown (B-C). In some specimens the dorsal scales have bluish edges (F).