Stria

Definition

A fine, longitudinal groove, ridge, or line on the cuticle or other hard surface; in arthropods, typically refers to parallel grooves running lengthwise along the elytra, pronotum, or other sclerites. Striae may be impressed (grooves) or elevated (carinae) and serve as key diagnostic characters in many beetle families and other insect groups.

Etymology

Latin stria, 'furrow, channel, flute of a column'

Example

Ground beetles (Carabidae) are often identified to genus by the number and arrangement of striae on the elytra—some species have deeply impressed striae with distinct punctures, while others have nearly smooth elytra with striae obsolete or absent.

Synonyms

• striation

Related Terms

• elytron
• Sulcus
• carina
• punctation
• Sculpture
• Costa
• interstria

Usage Notes

In entomology, 'stria' usually implies a longitudinal (anteroposterior) orientation; transverse grooves are more often termed sulci or furrows. The spaces between striae on elytra are called interstriae. The term is sometimes used loosely for any fine linear marking, but specialists distinguish true striae (structural grooves/ridges) from color patterns or microsculpture. In arachnology, striae may refer to grooves on the carapace or leg segments. Not to be confused with the unrelated medical term striae (stretch marks).