pedipalpus

Pedipalpus, singular for pedipalp and often rendered as pedipalpus or pedipalp in English, is one of the paired appendages located near the mouth on the cephalothorax of chelicerate arthropods. In chelicerates such as spiders and scorpions, the pedipalp is the second pair of appendages after the chelicerae and shares the basic limb segments (coxa, basis, femur, patella, tibia, tarsus), though it frequently carries specialized structures that reflect its function.

In spiders, pedipalps show marked sexual dimorphism. In males, the distal segments are modified into a complex copulatory organ, the palpal bulb, used to transfer sperm to the female during mating. In females and in many species of males at other life stages, pedipalps function primarily as sensory and manipulative limbs, helping to handle prey and explore the environment.

In scorpions, the pedipalps are enlarged pincers or chelae with movable fingers, used for grasping prey, defense, and communication. The robustness and shape of the pedipalpal claws vary among scorpion families and can be diagnostic for identification.

In other chelicerates such as harvestmen (opiliones), mites, and ticks, pedipalps may be shorter or more slender and serve feeding, sensory, or locomotor roles. Across chelicerates, pedipalps are integral for interaction with the environment, prey capture, and, in some lineages, reproduction.

Etymology: pedipalp derives from Latin pedipālus, meaning “foot palp.” The term pedipalpus is a Latinized variant encountered in some texts; pedipalp is the more common English form.