In a remote forest fragment in Tanzania, scientists have made a remarkable discovery: a uniquely-colored horned viper extending over two feet long (643 millimeters) that evolved from its closest relative over two million years ago. Unfortunately, however, the new species—named Matilda’s horned viper (Atheris matildae)—survives in a small degraded habitat and is believed to be Critically Endangered. Given its scarcity, its discoverers are working to preempt an insidious threat to the new species.