Pleidae

Definition

A family of minute aquatic true bugs (Hemiptera) commonly called pygmy backswimmers. Distinguished from the larger backswimmer family Notonectidae by their compact, rounded-oval body form, reduced size (typically under 3 mm), and habit of swimming right-side up rather than inverted. The family comprises approximately 52 species in four genera with cosmopolitan distribution in standing freshwater habitats, absent only from polar regions and remote oceanic islands.

Etymology

From Greek plein 'to swim' + -idae (family suffix).

Example

Plea minutissima, a widespread Palearctic species, inhabits ponds and ditches where it preys on small crustaceans and insect larvae, often detected by the silvery air bubble carried beneath the abdomen for respiration.

Synonyms

• pygmy backswimmers

Related Terms

• Notonectidae
• Nepomorpha
• Corixidae
• air-store respiration
• pleuston

Usage Notes

Distinguished from Notonectidae (common backswimmers) by morphology and swimming posture; Pleidae swim dorsal side up, lack the elongate hind legs of notonectids, and are substantially smaller. Formerly treated as subfamily Pleinae within Notonectidae, now universally recognized as distinct family. The family is placed in superfamily Pleoidea or alternatively treated as basal lineage within Nepomorpha depending on phylogenetic analysis.