Anisoptera

Definition

An infraorder of predatory flying insects within the order Odonata, comprising the true dragonflies. Adults are distinguished from damselflies (suborder Zygoptera) by their robust bodies, widely separated compound eyes, and hindwings broader than forewings with a distinctive notch (petiole) at the base; at rest, wings are held horizontally or slightly forward, never folded together above the body. The name reflects this wing asymmetry (Greek: anisos 'unequal' + pteron 'wing'). Larvae are aquatic, robust, and breathe through rectal gills. Anisoptera includes approximately 3,000 extant species across three superfamilies: Aeshnoidea (darners), Cordulegastroidea (spiketails and relatives), and Libelluloidea (skimmers and relatives).

Etymology

Greek anisos ('unequal, uneven') + pteron ('wing'), referring to the unequal size and shape of forewings and hindwings in dragonflies.

Example

The green darner (Anax junius), a large migratory species in the family Aeshnidae, exemplifies Anisoptera with its powerful flight, eyes that meet at the top of the head, and larvae that actively pump water through their rectal chamber for jet-propelled locomotion and respiration.

Synonyms

• Epiprocta (in part, disputed)

Related Terms

• Zygoptera
• Odonata
• dragonfly
• damselfly
• Epiprocta
• petiole
• rectal gills
• Aeshnidae
• Libellulidae
• compound eye
• hemimetabolous

Usage Notes

Anisoptera is universally ranked as infraorder within Odonata in modern systems, though some older treatments treated it as suborder. The contrasting suborder/infraorder Zygoptera contains damselflies, which fold wings together above the body at rest and have eyes more widely separated. The plant genus Anisoptera (family Dipterocarpaceae) is an unrelated homonym.