Mesoscutellum

Definition

The posterior median sclerite of the mesonotum, located behind the mesoscutum and between the mesopleura; typically triangular or shield-shaped in Hymenoptera and many other insects, often bearing axillary sclerites laterally and overhanging the propodeum or scutoscutellar suture.

Etymology

New Latin, from Greek mesos (middle) + Latin scutellum (small shield), diminutive of scutum (shield)

Example

In ichneumonid wasps, the mesoscutellum is often laterally carinate and projects posteriorly over the propodeum, a character used to distinguish subfamilies; in bumble bees (Bombus), it forms a rounded posterior lobe between the wing bases.

Synonyms

• scutellum of the mesonotum
• mesonotal scutellum

Related Terms

• mesoscutum
• scutellum
• axilla
• notaulus
• propodeum
• postscutellum
• scutoscutellar suture
• Metanotum

Usage Notes

Distinguished from the metascutellum (of the metanotum) and the general term 'scutellum,' which without prefix often refers to the mesoscutellum in Coleoptera. In Hymenoptera systematics, mesoscutellar shape, carination, and pubescence patterns are diagnostic at tribal and generic levels. The term is sometimes shortened to 'scutellum' in hymenopterological literature, but 'mesoscutellum' is preferred when precision across insect orders is required.