Anonychomyrma

Anonychomyrma species are common in moist to semi-arid forested areas (and are less common in rain forests). They nest either in soil with or without coverings, or arboreally in living or dead wood. Workers forage in conspicuous trails on the ground and on tree trunks. Although not studied in detail, they seem to be general predators and also collect plant juices. Some species are associated with the caterpillars of selected butterflies. Nest sizes are moderate to large, ranging from 500 to tens of thousands of workers. When disturbed, most species elevate their gasters and release strong, acrid smelling chemicals as a defensive measure.

Anonychomyrma differs from Iridomyrmex in habitat preferences and general ecology. Anonychomyrma prefers moister sites and is more often arboreal, while Iridomyrmex occurs primarily in drier sites and is predominantly terrestrial.



Worker of A. depilis from Queensland.



Worker of A. gilberti from Queensland.



Foragers feeding on a Camponotus worker found on a Eucalyptus trunk.

Identification
The front margin of the clypeus (just above the mandibles) is flat or convex. The scapes are about as long as the head. The first (apical) tooth of the mandible is only slightly longer than the second (subapical) tooth. The eyes are larger in diameter than the maximum diameter of the scape and are located relatively downward on the head near the mandibles. The petiole is upright and at most only moderately inclined forward.

In addition to the characters listed above, Anonychomyrma workers can be recognised by their usually square or slightly heart-shaped heads and compact bodies with domed pronotum, mesonotum and propodeum. Many species also produce a distinct odour that is often noticeable for quite a distance.

Extended diagnosis: Worker: Mandible with apical tooth slightly longer than subapical, basal angle distinct and with a well developed tooth or angle separating the masticatory and basal margins, and basal margin denticulate along entire surface; gastral compression absent (gaster circular in cross section); fourth gastral sternite keel-shaped posteriorly; petiolar scale vertical and varying from not inclined anteriorly to moderately inclined anteriorly but with the anterior and posterior faces approximately the same length.

Queen: Anterolateral clypeal margin with the corners expanded slightly anterior of the mediolateral region, and the entire margin with 14 to 26 short erect setae; dorsal face of propodeum longer than declivitous face; 28 to 40 erect hairs on the mesoscutum.

Male: Mandible with 5 to 9 teeth, 0 to 4 denticles, a distinct basal angle (or if the angle is weakly defined, the masticatory and basal margins are readily separable), and with the basal margin denticulate along its entire surface.

Distribution and Habitats
Australian distribution

Regional Species Lists

 * Australia

Keys to Species

 * Australia