Mexican Long-nosed Bat

They are sooty brown in color, with a darker dorsally and lighter ventrally. Individual hairs are white at the base, and silver at the tips. Their forearms are 54–59 mm (2.1–2.3 in) long. They have moderately-furred interfemoral membranes, and their short tails only have three vertebrae. Their muzzles are elongated, and their tongues are long and tipped with filiform papillae. The tongue attaches at the posterior side of the sternum. Their nose-leafs are triangular and erect. The average mass is 24 g (0.85 oz) Their ears are 15 mm (0.59 in) long. Like other nectarivores, this species has reduced teeth, missing the third molar while the other two molars are weakly cusped. Loss of teeth and dental ridges indicate accurately that their diet does not necessitate biting and chewing.

The species is found in southern Texas, Arizona, and New Mexico from June through August. It is found in central Mexico throughout the rest of the year. They roost primarily in caves and mines, but can also be found in unoccupied buildings, hollow trees, and even sewers. While it has been alleged that the bats are found as far south as Guatemala, the IUCN disputes this notion, and lists its southernmost occurrence as central Guerrero.

Little research has focused on reproduction in this species, but there are speculations based on this limited body of work. Mating occurs in November and December in Cueva del Diablo, which coincides with the greatest availability of food around the cave. They likely have a polygynandrous mating system, where males and females mate multiple times with different individuals. Because male testes are significantly larger during the mating season and females mate with multiple males, there is likely sperm competition between males. Females are hypothesized to exhibit sperm storage or embryonic diapause. It is thought that they are monoestrous; therefore they only breed once per year. Birth likely occurs during May, during female migration to northern Mexico or the southwestern United States. Litters likely consist of a single pup. Males are likely non-migratory, and adult males are rarely encountered in the United States. Females form maternity colonies in the northern parts of their range, with lactating females and their young arriving at a cave in Texas in June. There are records, however, of pregnant females arriving as early as mid-April, which shows that some females do not give birth until completing migration. Based on censuses, it is thought that the pups do not become volant until July. The adult females and their young leave Texas in August.