Protobothrops himalayanus

The Himalayan lance-headed pit viper is a rare, venomous pit viper endemic to Asia. It is a large, thin, cylindrical snake with a dark brown head with red-brown streaks by the eyes, an olive body and tail with black and brown bands, and eyes in varying shades of brown (Wikipedia, general species account).

The Reptile Database lists southern Tibet, Nepal, Bhutan and Sikkim. The account used here gives no information on habitat, diet or breeding.