Ophryacus is a genus of pit vipers endemic to Mexico. The name is derived from the Greek word ophrys (á½ÂÃÂÃÂÃÂÃÂ), which means "brow", and the Latin word acus, which means "needle", an allusion to the characteristic horn-like scales over the eyes. Currently, three species are recognized and no subspecies.
The larger of the two species, O. undulatus, grows to between in length. They are characterized by the presence of a single scale over the eye that takes the shape of either a long and relatively slender spine, or a flattened horn. Often, other supraocular scales are also shaped in such a way that they project slightly.
They are restricted to the mountains of eastern, central and southern Mexico.
<span style="font-size:100%;"><sup>T</sup></span>) Type species.