Holoptic

Definition

Having compound eyes that meet or nearly meet along the median dorsal line of the head, often covering most of the dorsal head surface and leaving little or no visible frons between them.

Etymology

Example

Male horse flies (Tabanidae) are typically holoptic, with eyes that meet broadly on top of the head, whereas females are dichoptic with widely separated eyes.

Related Terms

• dichoptic
• cycloptic
• compound eye
• Frons
• vertex

Usage Notes

Primarily describes male dipterans, though also occurs in females of some groups (e.g., certain Coleoptera, Odonata: Anisoptera, Archaeognatha). Contrasts with dichoptic (eyes widely separated) and cycloptic (single median eye, as in some larvae). The condition is often sexually dimorphic and can be a key diagnostic character for species identification in flies.