Dorylus

Homology Weekly: Petiole, Postpetiole and “Tubulation”

The isolated second abdominal segment constitute the characteristic petiole (blue) in ants. <i>Pachycondyla stigma</i> worker (Scanning Electron Micrograph, Roberto Keller/AMNH)

An isolated second abdominal segment constitutes the characteristic petiole (blue) in ants. Pachycondyla stigma worker (Scanning Electron Micrograph, Roberto Keller/AMNH)

The easiest way to know you are looking at an ant is to pay attention to its waist: if it consists of one or two nicely isolated segments you can be sure you made a positive identification. The basal condition for the family, common to all ants, is to have the second abdominal segment in the shape of a node or scale and distinctly isolated from the rest of the abdomen to form a petiole (remember that the first abdominal segment is coupled to the thorax as the propodeum). The functional advantage of such novel architecture seems to be an enhanced articulation between body segments, and thus greater mobility¬†for a posterior part of the body that bears the ant’s weapons in the form of a sting or other specialized chemical producing¬† organs like the acidopore.1
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  1. This post is dedicated to my long time friend and colleague Francisco Vergara-Silva
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Homology Weekly: Sensillae Trichoidea

Thursday, January 8th, 2009 | Ants, Homology Weekly, Morphology | Comments Off on Homology Weekly: Sensillae Trichoidea

Detail of the right antennal apex of a Dorylus helvolus worker (Scanning Electron Micrograph, Roberto Keller/AMNH)

Detail of the antennal apex of a Dorylus helvolus worker (Scanning Electron Micrograph, Roberto Keller/AMNH)

This image shows the surface of the tip of the antenna in the African driver ant Dorylus helvolus. The tongue-shaped structures are one of the many types of hair-like sensory organs called sensillae trichoidea (Latin for, well, hair-like sensory organs). These organs are basically composed of a central piece of cuticle in the shape of a long filament or short paddle inserted into a socket and kept in place by a membranous ring. The central piece, thus, can freely move in all direction allowed by the socket. › Continue reading

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And as we discussed last semester, the Army Ants will leave nothing but your bones.
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