a small median appendage between the claws of the tarsi of many insects and arachnids

Many insects possess a lobe or spine between the two claws at the end of the tarsus (the final segment in the leg of the insect). This lobe or spine is called an empodium.

Empodium Legend: 1 - Pulvilli, 2 - Claw, 3 - Empodium