Archetype

Homology Weekly: Tagmata

Profile view of a Ponera pennsylvanica worker showing primary tagmosis. Red: head; yellow: thorax; blue: abdomen (Scanning Electron Micrograph, Roberto Keller/AMNH)

When a group of successive segments along the arthropod body form a distinct section (by fusion, for example), the division is called a tagma (pl. tagmata). In the case of hexapods (= insects plus their primitively wingless cousins) the body segments are arranged into the three familiar tagmata: head, thorax and abdomen. › Continue reading

Tags: Abdomen, Alitrunk, Apocrita, Head, Mesosoma, Metasoma, Ponera, Tagma, Tagmata, Thorax

Homology Weekly: Hypopygium

Last week’s post featured the acidopore: a modification of the ventral plate in the last visible segment of the abdomen in females, as it occurs in the formicine subfamily of ants (e.g., wood ants, carpenter ants, weaver ants). Counting from front to back, this ventral plate is part of the seventh abdominal segment and is denoted by a special term in insects: hypopygium (pl. hypopygia). It is colored in red in the images below.

Abdomen of a Leptogenys sp worker from Nepal, profile view (Scanning Electron Micrograph, Roberto Keller/AMNH)

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Tags: Abdomen, Hypopygium, Leptogenys, Morphology