Snakes northern Thailand—illustrated checklist

In this illustrated checklist “northern Thailand” is considered as consisting of 17 provinces:
Upper North: Mae Hong Son, Chiang Mai, Chiang Rai, Phayao, Nan, Lamphun, Lampang, Phrae, Uttaradit. Lower North: Tak, Sukhothai, Phitsanulok, Phetchabun, Kamphaeng Phet, Phichit, Nakhon Sawan and Uthai Thani.

Typhlopidae (Blind Snakes)
Family: Typhlopidae. Small and very small snakes resembling earthworms, shiny black or grayish-brown, NO enlarged ventral shields (all body scales similar size), head indistinct, reduced eyes.
Figure 1:
1. Indotyphlops (Ramphotyphlops) albiceps, the White-headed Blind Snake. A.  A specimen from Mueang District, Chiang Mai.
2. Indotyphlops (Ramphotyphlops) braminus,the Flowerpot Snake. B. A specimen from Bangkok (picture© Jonathan Hakin, with thanks!)
3. Argyrophis (Typhlops) diardii (Diard’s Blind Snake). A relatively large blind snake, reaching a length of 40 cm. Upperside shining dark grey, belly light  grey or whitish. Often found in decomposed wood. C. A DOR from Phop Phra District, Tak. D. Specimen from Umphang, Tak.
4. Typhlops porrectus, also recorded in northern Thailand, is not depicted here.

Cylindrophiidae (Pipe Snakes)
Family: Cylindrophiidae. “Primitive snakes”, one species known from Thailand.
NO enlarged ventral shields (all body scales similar size), head small and indistinct.
Figure 2:
5. Cylindrophis ruffus, the Red-tailed Pipe Snake. A black snake reaching a length of 80 cm, upper side with (often indistinct) white or pale orange crossbars, belly with alternating black and white blocks. Very short pointed tail with orange marking. In northern Thailand common in the well-watered lowlands of Uttaradit and the provinces of the Lower North of northern Thailand. A-B. specimens from Mueang District, Uttaradit. C. Ventral (belly) view of a juvenile from Sam Ngao District, Tak.

Xenopeltidae (Sun Beam Snakes)
Family: Xenopeltidae. Primitive snakes with shovel-like flattened head and strongly iridescent dorsal scales. One species is known from Thailand.

Figure 3.
6. Xenopeltis unicolor, the Sunbeam Snake. Upper side shiny purplish-grey, belly white, head flattened (shovel-like). Reaching a length of 1 m. Common throughout the valleys and lowlands of northern Thailand, occasionally found at higher elevations. A. Specimen from San Patong District, Chiang Mai. B. Pua District, Nan. C. Captive specimen from Mae Rim District, Chiang Mai showing its white belly, while devouring a Striped Keelback (Amphiesma stolatum). D. Specimen showing the characteristic scalation of the upperside of the head.
More about this snake (in Dutch): click here :

Pythonidae (Pythons)
Family: Pythonidae. Large powerful constrictors reaching maximum lengths of 3-10 m. Three specimens are known to occur in northern Thailand.

Figure 4.
7. Malayopython (Broghammerus/Python) reticulatus, the Reticulated Python.
Characteristic pattern with zigzags and elliptic white dots, yellow head. Widely distributed in northern Thailand. Specimens of more than 7 m length have been reported. A. A large, about 4 m long specimen in captivity at Wat Mae Kampong, Mae On Village, Mae On District Chiang Mai. Pythons often rest in positions similar to this “noodle ball”. B. Head and neck of a DOR specimen from San Pa Tong District, Chiang Mai. There is no arrowhead mark on the upper side of the skull as there is in Python molurus. C-D: A specimen that was captured in lowland Mueang Chiang Mai and subsequently released. E: An about 4 m long specimen spotted in Khao Yai National Park, Pak Chong District, Nakhon Ratchasima.

Figure 5.
8. Python molurus (bivattus), the Burmese or Indian Python. Sharp V-shaped mark on the upper side of the head. The species occurs throughout northern Thailand, but is somewhat less common than the Reticulated Python. A-B: Juvenile from Mueang District, Chaiyaphum (Northeast-Thailand).

9. Python brongersmai, the Short or Blood Python, has not been illustrated here. In northern Thailand this rare species has only been reported from the very south of the Lower North.

Xenodermatidae (Strange-skinned Snakes)
Family Xenodermatidae. Snakes characterized by dorsal scales that are not overlapping but embedding in the interstitial skin, hardly touching each other. One species is known from northern Thailand.

Figure 6.
10. Parafimbrios lao. This species can be easily distinguished by the way each ventral shield articulates with both a normally-sized dorsal scale and with a much enlarged one. A-B. The only living specimen thus far reported from Thailand. In November 2016 it was found in evergreen forest at about 1400 m asl in Nan Province. Only recently (2015) it was discovered in northern Laos and described as a new species. Now it is known from six specimens from Laos, Vietnam and Thailand. Not all of those specimens show a white collar as seen in the living Thai specimen in the picture above.

Pareidae (Snail Eaters or Slug Snakes)
Family: Pareidae. Rather modestly-sized (30-70 cm) snakes with blunt heads, mainly active at night. A central groove is lacking between chin shields. Four species are known to occur in northern Thailand.

Figure 7.
11. Pareas carinatus or Keeled Slug Snake. Upperside yellowish-brown or orange-brown, often with a fine dark reticulation. Body laterally compressed. Red eye with black vertical eliptic pupil. Common throughout much of northern Thailand in forested or semi-cultivated hills at elevation of 300-900 m asl. A-B: Specimens from Tha Song Yang District, Tak, in evergreen forest at about 700-800 m asl. C: Details of the head scalation of a specimen from Mae Chaem District, Chiang Mai, showing a relatively large supraorbital and preorbital and a prefrontal shield (asterix) that does not enter the orbit. D: A slightly paler specimen from Mae Chan District, Chiang Rai. E: A brightly colored juvenile from Chiang Dao District, Chiang Mai.

Figure 8.
12. Pareas hamptoni or Hampton’s Slug Snake. This snake superficially closely resembles Pareas carinatus but can be distinguished from the latter by its somewhat larger size, its larger number of ventral shields and the prefrontal shields that enter the orbit. It occurs in evergreen forest at high elevation (1000-1700 m asl). A. A specimen from Khun Yuam District, Mae Hong Son. B-C. A specimen from Chiang Mai’s Mae Wang District

Figure 9.
13. Pareas margaritophorus, the Smooth Bicolored-spotted Snail Eater.
This grey little snake (max. length 45 cm) is ornamented with many bicolered (black-and-white) spots the size of one dorsal scale. All dorsal scales are smooth. Most specimens have a nuchal collar that can be entire or tripartite which color varies from white and pale sulphur to pink or bright orange. This species is common throughout northern Thailand where it prefers forested or cultivated areas at elevations of 300-700 m. A-B: Specimens from Tha Song Yang District, Tak. C: Specimen from Bo Kluea District, Nan, D: Specimen from Mae On District, Chiang Mai.

Figure 10.
14. Pareas macularius, the Keeled Bicolored-spotted Snail Eater.
This species has often been confused with the former (Pareas margaritophorus) as its ground color is also grey and it is also ornamented with black-and-white spots. However, there are many differences: Pareas macularius is larger (specimens measuring more than 60 cm have been recorded), has 5-9 rows of dorsals that are keeled, has a differently shaped nuchal color of which the color is never yellow, pink or orange. The 7th, largest spoon-shaped supralabial nearly always has a large intensely black blotch (lacking in Pareas margaritophorus). This snake is common throughout the mountains of northern Thailand in forested or cultivated areas at elevations of 800-1700 m a.s.l. A. A juvenile from Khun Yuam district, Mae Hong Son. B-C: Two different specimens from Mueang Pan District, Lampang, showing the considerable variation in the shape of the finely speckled nuchal color. D.Details of the head and nuchal collar of a specimen from Phu Hin Rong Kla National Park, Nakhon Thai District, Phitsanulok.


15.Enhydris bocourti
16.Enhydris enhydris
17.Enhydris jagorii (no picture)

18. Enhydris plumbea, the Yellow-bellied or Plumbeous Water Snake. Little snake (max. length 60 cm) common in well-watered lowlands throughout the northern region. Upper side brownish or greenish-bronze. Belly pale yellow or dark yellow.  A. A specimen from Mueang District, Chiang Mai. B. DOR-specimen from Loei Province, Northeast-Thailand. C. An adult specimen from Mueang Chiang Mai preying on a frog.
19. Enhydris subtaeniatus,
20. Homalopsis mereljcoxi,

21. Ahaetulla nasuta, the Long-nosed Whip (Vine) Snake, very slender grass green snake measuring up to 150 cm.  Head elongated with long, grooved pointed snout which is extended with a little appendix of the rostrum. Belly paler green than the upper side with a pair of narrow pale green or whitish  ventrolateral stripes. Golden eye with black horizontal slit-pupil. Locally common in lowlands with agricultural fields. A. An adult specimen in captivity at the Snake Farm in Bangkok. B. Details of the head of a specimen from xxx. C. Adult hidden in a tangle of stalks and vines, Nong Phai District District, Phetchabun.
22. Ahaetulla prasina. Very slender snake with pointed snout, that can reach a length of 2 m. Eye with horizontal slit-pupil. Color variable: grey, blueish-green, silver-grey, but in most of northern Thailand mostly bright “grass” green. When aroused the anterior part of the body is expanded showing black and white little bars on the edges of the scalen and the interstitial skin.
A. Pale blue-green adult from Chiang Klang District, Nan. B. Bright green specimen from Wiang Kaen District, Chiang Rai. C. Pale orange-brown juvenile from Mueang Pan District, Lampang. D. Bright green adult, resting at night in vegetation, showing its slender, long body. Phu Chi Fa, Wiang Kaen District, Chiang Rai.
23.  Boiga cyanea
24.Boiga multomaculata
25.Boiga siamensis
26.Calamaria lumbricoidea
27.Calamaria pavimentata
28.Chrysopelea ornata
29. Coelognathus flavolineatus
30.Coelognathus radiatus
31. Dendrelaphis cyanochloris, the Blue Bronzeback. 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. Upperside head of adult from Pai District, Mae Hong Son. E. Juvenil from Phu Hin Rong Kla National Park, Nakhon Thai District, Phitsanulok.
32. Dendrelaphis ngansonensis
33. Dendrelaphis nigroserratus or Saw-tooth-necked Bronzeback. 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 adult from Phop Phra District , Tak. D. Adult from Kaeng Krachan National Park, Kaeng Krachan District, Phetchaburi.
34. Dendrelaphis pictus
35.Dendrelaphis subocularis
36.Dinodon septentrionalis
37. Dryocalamus davisonii
38.Dryophiops rubescens
39.Gongylosoma scripta
40. Gonyosoma oxycephalum
42. Gonyosoma prasinum
43. xxxxxx
44. xxxxxx
45. Lycodon capucinus
46. Lycodon fasciatus
47. Lycodon laoensis
48. Lycodon subcinctus
49. Oligodon cinereus
50. xxxxxx
51. Oligodon fasciolatus
52. Oligodon cf fasciolatus.
53. Oligodon inornatus (no picture)
54. Oligodon joynsoni
55. Oligodon mouhoti
56. xxxxxx
57. Oligodon taeniatus
58a. Oreocryptophis porphyracea porphyracea
58b. O. p. coxi
59. Orthriophis taeniurus (helfenbergeri)
60. Plagiopholis nuchalis
61. Plagiopholis blakeswayi (no picture)
62. Psammophis indochinensis
63. Ptyas carinata
64. Ptyas korros
65. Ptyas mucosa
66. Ptyas nigromarginata
67. Sibynophis collaris
68. Amphiesma stolatum, the Striped Keelback. Dark brown snake that reaches a length of 70 cm with a pair of light buff stripes that extend from the neck to the end of the tail. Anteriorly, a row of blackish, squarish blotches in between the stripes. Upper side of the head slate or ashy grey. The belly is white. Occasionally specimens with a yellow throat and chin, and bronze head, are seen (A). The dorsal scales are strongly keeled. When the anterior body is a little expanded, it shows a reticulated pattern (B). This snake is locally common in the northern region. A. An adult from an longan orchard in Lamphun’s Li District. B-C. Adult specimens, both from Mae Rim District, Chiang Mai.
More about this species (in Dutch), click here .
69.Hebius bitaeniatum
70.Hebius deschauenseei
71.Hebius khasiense
72.Opisthotropis spenceri
73.Parapaaaa (no picture)
74.Psammodynastes pulverulentus
75.Rhabdophis chrysargos
76.Rhabdophis nigrocinctus
77.Rhabdophis subminiatus
78.Sinonatrix percarinata (false?)
79.Sinonatrix yunnanensis
80.Xenochrophis flavipunctatus
81.Xenochrophis piscator
82.Xenochrophis punctulatus (false?)
83.Pseudoxenodon macrops
84.Bungarus candidus
85Bungarus fasciatus
87.Calliophis maculiceps
88.Sinomicrurus macclellandi
89.Naja kaouthia
90.Naja siamensis
91.Ophiophagus hannah
92.Calloselasma rhodostoma
93.Daboia siamensis
94.Ovophis monticola
96.Trimeresurus albolaris
97.Trimeresurus gumprechti
98.Trimeresurus macrops
99.Trimeresurus popeiorum