dactylopatagium

Dactylopatagium is a wing membrane of bats (order Chiroptera). It is the portion of the patagium that extends between the digits (fingers) II–V and the body, forming the principal surface used in flight. The dactylopatagium is continuous with the propatagium at the shoulder and with the plagiopatagium along the wing’s trailing edge, and it is supported by the bones of the forelimb, especially the metacarpals and phalanges. Its skin is thin and hairless, and highly elastic, allowing the wing to fold when not in use.

In bats, the size and shape of the dactylopatagium vary among species and are related to flight style and ecology. Some species have a relatively expansive dactylopatagium that increases wing area and lift for slow, maneuverable flight, while others possess a more compact membrane suitable for fast, sustained flight. The membrane can differ in thickness and elasticity depending on lineage and ecological needs.

Functionally, the dactylopatagium provides lift and wing camber, distributes aerodynamic loads across the wing, and participates in wing folding during roosting. Its mechanical properties influence flight dynamics, maneuverability, and energy efficiency, making it a focus in studies of bat locomotion and evolution.