Clavus

Definition

In Hemiptera, the membranous or partially sclerotized basal region of the hemelytron (forewing) that lies adjacent to the scutellum, bounded distally by the claval suture and often overlapping the scutellum at rest. The clavus typically contains fewer veins than the corium and may be membranous, leathery, or pigmented depending on the taxon; its shape and texture are diagnostic characters in many heteropteran families.

Etymology

Latin clavus ('nail, spike'), referring to the elongated, often nail-like shape of this wing region in many true bugs.

Example

In pentatomid stink bugs (Hemiptera: Pentatomidae), the triangular clavus is distinctly darker than the surrounding corium and extends to the scutellar apex, forming a characteristic 'scutellar triangle' used in species identification.

Related Terms

• hemelytron
• Corium
• scutellum
• claval suture
• Membrane
• Hemiptera
• forewing

Usage Notes

The clavus is specific to the hemelytra of true bugs and should not be confused with the clavus of sunfish (Molidae) or the medical term for corns. In some families (e.g., Miridae), the clavus is reduced or fused with the corium; in others (e.g., Coreidae), it is large and conspicuous. Venation patterns within the clavus (presence or absence of a claval vein) are important in subfamily-level classification.