What is "propodeum"

Propodium \Pro*po"di*um\, n.; pl. Propodia. [NL. See Propodiale.] (Zo["o]l.)

1. The anterior portion of the foot of a mollusk.

2. The segment which forms the posterior part of the thorax of a hymenopterous insect. [Written also propodeum.]

n. The first abdominal segment in wasps, bees and ants, fused with the thorax to form the mesosoma.

The propodeum is the first abdominal segment in Apocrita Hymenoptera ( wasps, bees and ants). 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.