Wikipedia
Viperinae
Common names: pitless vipers, true vipers, Old World vipers, true adders.
The Viperinae, or viperines, are a subfamily of venomous vipers endemic to Europe, Asia and Africa. They are distinguished by their lack of the heat-sensing pit organs that characterize their sister group, the subfamily Crotalinae. Currently, 12 genera and 66 species are recognized. Most are tropical and subtropical, although one species, Vipera berus, even occurs within the Arctic Circle.