Microcoryphia

Definition

An order of apterygote insects (bristletails) characterized by a humped thorax, large compound eyes that meet dorsally, and three caudal appendages (two cerci and a median caudal filament). Members possess eversible vesicles on the ventral surface of abdominal segments and retain several ancestral traits, including monocondylic mandibles and a jumping mechanism using the thorax and abdomen. The order comprises approximately 500 described species, primarily in the family Machilidae, and represents one of the most basal extant insect lineages, with fossil records extending to the Middle Devonian.

Etymology

From Greek mikros (small) + koryphē (head), referring to the relatively small head positioned anterior to a large, humped pronotum.

Example

Petrobius maritimus, the sea bristletail, is a common intertidal species of Microcoryphia found along rocky coasts of Britain and northwestern Europe.

Synonyms

• Archaeognatha

Related Terms

• Apterygota
• Apterous
• cercus
• caudal filament
• monocondylic
• Zygentoma
• Thysanura
• Machilidae
• evolutionary primitive

Usage Notes

Microcoryphia and Archaeognatha are alternative valid names for the same order; Archaeognatha is now more commonly used in modern literature. The group was historically united with Zygentoma (silverfish) under the abandoned name Thysanura. Microcoryphia is distinguished from Zygentoma by its jumping ability, dorsally meeting eyes, and presence of abdominal styli and eversible vesicles. The term is sometimes restricted to the suborder rank when Archaeognatha is used for the order.