Also known as the Usambara bush viper, or eyelash bush viper, the horned bush viper is a species of bush viper (Atheris spp.) which is endemic to the Usambara and Uzungwe Mountains in Tanzania. Horned bush vipers are arboreal and inhabit high altitude woodlands and forests. Like other vipers horned bush vipers are venomous and use their venom to dispatch prey. Like other members of the genus Atheris, horned bush vipers likely active at night and feed on a variety of small vertebrates.