Nannochoristidae

Definition

A relict family of scorpionflies (order Mecoptera) comprising a single extant genus, Nannochorista, with eight species distributed in New Zealand, southeastern Australia, Tasmania, Argentina, and Chile. Distinguished by aquatic, predatory, elateriform larvae that hunt chironomid larvae in shallow streams—unique among mecopterans, which typically have terrestrial, eruciform larvae. Adults are associated with riparian and montane bog habitats and are thought to feed on liquid resources such as nectar or fruit juices. The family's distinctive morphology and biology have led some authors to elevate it to a separate order, Nannomecoptera, and phylogenetic studies have proposed a close relationship to Siphonaptera (fleas).

Etymology

From Greek nannos (dwarf) + choristos (separated, distinct), referring to the family's small size and isolated phylogenetic position.

Example

Larvae of Nannochoristidae are the only aquatic mecopterans, using their elongated, slender bodies to pursue prey among streambed substrates in Tasmanian montane streams.

Synonyms

• Nannomecoptera (order rank, controversial)

Related Terms

• Mecoptera
• Siphonaptera
• scorpionfly
• elateriform
• eruciform
• relict distribution
• Gondwanan distribution
• aquatic insect larvae
• chironomid

Usage Notes

Sometimes treated as the monotypic order Nannomecoptera due to its divergence from other scorpionflies; however, most classifications retain it within Mecoptera. The family's disjunct Southern Hemisphere distribution (Australasia + southern South America) is classic Gondwanan. Larval morphology (elateriform, aquatic) contrasts sharply with the caterpillar-like, terrestrial larvae of other mecopteran families.