Short-Tailed Bat (c) Richard Brown
We've managed to narrow it down to under the broad umbrella of American Leaf-Nosed Bats, in the sub-family Short-Tailed Bats. In that family it can be one of four species...If anyone knows which one it is I'd sleep better tonight. The presence of warts on its chin (a row of small warts surrounding a large central wart), separates this bat from other sub-families in the Leaf-Nosed Bat family, which incidentally is the largest family of Bats in Costa Rica.
Short-tailed Bats are frugivores, and tend to be specialists of plants of the genus Piper. Pipers are the Pepper Plants, or Pepper Vines. This plant genus also contains a species of pepper that was used by the Aztecs to spice the first Cocoa drinks in Mexico. Its funny to think that the Short-Tailed Bat was partially responsible for the bed-time beverages of the Aztecs.
Because of this, Short-Tailed Bats are also known as Piper-Eating Bats. They play a mega vital role of seed dispersal in the rainforest. This one, however, was dispersing seeds in the ladies washroom at Palo Verde National Park.