Propodeum

The propodeum^[a] is a term that can refer to unrelated structures in insects or in mollusks.

Propodeum labelled within the alitrunk of an ant worker

Insects

The first abdominal segment in Apocrita Hymenoptera (wasps, bees and ants) is known as the propodeum. It is fused with the thorax to form the mesosoma. It is a single large sclerite, not subdivided, and bears a pair of spiracles. It is strongly constricted posteriorly to form the articulation of the petiole, and gives apocritans their distinctive shape. There may be a suture between the propodeum and the thorax, like in Symphyta^[3] or not, and the presence or absence of such suture can aid in identifying specimens.

Mollusks

Thomas Henry Huxley's diagram of a hypothetical stem mollusk labels the propodeum shown at lower left as 'p.p.'

Propodeum is the anterior (frontal) part of the foot of a mollusk.^[4]

Notes

1. zooanatomical jargon derived from Ancient Greek: πρωπόδιον "forefoot", also as 'propodeon'^[1][2] or 'propodium'^{[attribution needed]}; plurals 'propodea', 'propodia', or by appending -s to the singular