Otonyctomys hatti Anthony, 1932, is a rodent commonly called the Yucatán vesper mouse. A medium-sized, brightly colored mouse, it is the only species in the genus Otonyctomys. It is endemic to the Yucatan Peninsula. It seems to have arboreal habits and occurs in semideciduous tropical forest and vegetation near water. It feeds on seeds, either on the ground or in shrubs, and soft-bodied fruits. It is considered a rare species throughout all of its geographic range but evaluation of its current conservation status is warranted.