Tubercle

Definition

A small, rounded, knob-like projection or nodule on the surface of an organism, especially on the cuticle of arthropods. In insects and arachnids, tubercles may serve as muscle attachment sites, bear setae or spines, function in camouflage or defense, or contribute to species-specific sculpturing used in taxonomy.

Etymology

From Latin tuberculum, diminutive of tuber 'lump, swelling'

Example

The pronotum of many stink bugs (Pentatomidae) bears lateral tubercles that vary in size and shape among species and are used in identification keys.

Synonyms

• nodule
• papilla
• mammilla

Related Terms

• spine
• seta
• carina
• tuberculate
• Cuticle
• Integument
• maculation
• sculpturing

Usage Notes

Distinguished from spines by being typically shorter, broader at the base, and non-articulated; from setae by lacking the socket (alveolus) and cuticular ring of a true setal base. 'Tuberculate' describes surfaces bearing numerous tubercles. In medical contexts the same word refers to the lesions of tuberculosis, but this meaning is unrelated to arthropod morphology.