either of two species (M. robusta and M. tuberculata) of small bats that are the only species in the rare bat family Mystacinidae, which is found only in New Zealand. They are about 6–7 cm (2.4–2.8 inches) long and have a short 1.8-cm (0.7-inch) tail. The fur is grayish brown and thicker than the fur of other bats. Close to the body the wing membranes are leathery, and the wings can be furled tightly within them. M. tuberculata is the most terrestrial bat, and it is very agile on the ground. In its forest habitat it may roost in hollow trees, caves, or crevices, and it sometimes digs tunnels in rotten wood. The diet of this species includes fruit, nectar, pollen, and insects. The young are born with their eyes open. M. robusta is probably extinct.