Spot Tail Pit Viper ( Trimeresurus erythrurus Cantor, 1839 )

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Scientific Name: 
Trimeresurus erythrurus (Cantor, 1839)
Regional Names: 
Spot Tailed Pit Viper, Red Tailed Pit Viper
Found in most of the north-east region of India. Probably found in wider areas touching peninsular India. This time its southernmost limit in India is mangroves of Sundarbans (West Bengal and Bangladesh). Also found in Bangladesh, Bhutan, Myanmar, Nepal and Thailand. Recorded from Arunachal Pradesh, Assam, Manipur, Meghalaya, Mizoram, Nagaland, Sikkim, Tripura, West Bengal.
Venom Type: 
Characteristics for identification: 

Looks like all other Green coloured Pit Viper of South-East Asia and not easy to identify it to species level. Superficially this species can be differentiated with other Green Pit Vipers by checking the presence of highly keeled scales on temporal region of head.


Average length- 50cm.
Maximum length- 105cm (Female), 57.5cm (Male).

Dorsal -
Body somewhat slender, covered with highly keeled scales. Upper body color green or yellowish-green with interscale color black. A fine white line starts from posterior of eyes and runs along the last dorsal row till the base of tail. Females usually with no such stripe or present in very indistinct form.

Ventral -
Belly color mostly yellowish-green or greenish white with darker color on edge. Subcaudal scales usually paired.

Head -
Head triangular, not depressed, covered with very small and strongly keeled scales; clearly broader than neck. Patternless green on top and upper lip color yellow or greenish-white, matching with belly color. Eyes have vertically elliptical pupil.

Tail -
Prehensile and rather short tail ends with a pointed tip. Marked with brown or dark brown spots.

Supralabial 9-13; first partially or completely fused with nasal; 1 or 2 rows of scales between supralabial and elongated subocular; supraocular narrow and entire; 11-14 scales between eyes; temporal scales small and highly keeled.
Highly keeled scales in 23/25:23/25:17/19 rows.
153-174 (Male), 151-180 (Female); anal undivided.
Sub Caudal: 
62-79 (Male), 49-61 (Female); usually paired or few unpaired.
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