Ditrysia

Definition

A major clade of Lepidoptera comprising roughly 98% of all moth species plus all butterflies, characterized by females possessing two separate genital openings: one for copulation (the copulatory pore, derived from the ostium bursae) and one for oviposition (the ovipore). This arrangement contrasts with the single fused opening (monotrysian condition) found in the more basal lepidopteran lineages. Ditrysia encompasses the vast majority of lepidopteran diversity, including all macro-moths and butterflies, and is divided into two primary sections: Tineina (containing many small moth families) and Cossina (containing the bulk of larger moths and butterflies).

Etymology

From Greek di- (two) + trysia (holes, openings), referring to the dual female genital openings that define the clade.

Example

The monarch butterfly Danaus plexippus, like all butterflies, belongs to Ditrysia; dissection of a female reveals the separate copulatory pore and ovipore characteristic of this clade.

Related Terms

• Monotrysia
• Glossata
• Heteroneura
• Eulepidoptera
• Apoditrysia
• Tineina
• Cossina
• ostium bursae
• ovipore

Usage Notes

Ditrysia is sometimes referred to as a 'division' in older literature, though 'clade' is now preferred. The term is used in both phylogenetic systematics and comparative morphology. When discussing female reproductive anatomy, specialists distinguish the ditrysian condition (two openings) from the monotrysian condition (single opening), with the latter representing the plesiomorphic state in Lepidoptera. The derived term Apoditrysia refers to a more exclusive subgroup within Ditrysia.