Tarsus

Definition

The distal segment of an arthropod leg, located immediately beyond the tibia and comprising a series of subsegments (tarsomeres) that typically terminate in one or two claws and often bear adhesive pads or pulvilli. In insects, the tarsus is usually divided into two to five tarsomeres and serves as the primary contact surface with the substrate; its morphology varies markedly across taxa, reflecting ecological specialization such as grasping, jumping, swimming, or pollen collection.

Etymology

From Latin tarsus, from Ancient Greek tarsos, meaning 'the flat of the foot' or 'ankle'.

Example

A honey bee worker possesses a five-segmented tarsus on each leg, with the basitarsus of the hind leg broadened and fringed to form the corbicula (pollen basket), while the foreleg tarsus bears a notch for antenna cleaning.

Synonyms

• telotarsus

Related Terms

• tarsomere
• claw
• empodium
• pulvillus
• tibia
• Femur
• Coxa
• Trochanter
• pretarsus
• Arolium

Usage Notes

The term is absolute (not relative) and refers specifically to the leg segment, not to the entire foot or to the homonymous ankle bones of vertebrates. In some arachnids and crustaceans, 'tarsus' may be applied to analogous distal leg segments, though specialists in those groups often prefer group-specific terminology. The plural 'tarsi' is standard in entomological literature. Do not confuse with 'tarsus' as a taxon name (e.g., the beetle Proterhinus tarsus) or with the anatomical term for the eyelid skeleton.