Monomorium carinatum

This species appears to be nocturnal: I have seen terrestrial foraging activity by workers near Newman, Western Australia Heterick (2001).

Identification
Heterick (2001) - A member of the monomorium group. Monomorium carinatum belongs to the Monomorium sydneyense complex, and closely resembles northern populations of that species. Some M. carinatum workers without strongly defined propodeal carinae may be confused with M. sydneyense, but can be distinguished by the laterally compressed propodeum, flattened trapezoidal promesonotum (viewed dorsally) and relatively larger eye.

Distribution based on Regional Taxon Lists
Australasian Region: Australia.

Nomenclature

 *  carinatum. Monomorium carinatum Heterick, 2001: 397, figs. 35, 136, 143 (w.) AUSTRALIA.

Worker
Holotype. HML 1.47; HL 0.53; HW 0.43; Cel 80; SL 0.38; SI 89; PW 0.30. Others. HML 1.25-1.56; HL 0.48-0.55; HW 0.36-0.46; Cel 76-86; SL 0.34-0.40; SI 84-94; PW 0.24-0.32 (26 measured).

As for the worker of M. sydneyense, but with the following apomorphies.

Head. Frons of head capsule smooth and shining with evenly spaced, appressed setulae, or longitudinally striate with well-spaced, appressed setulae. (Viewed laterally) compound eyes set at midline of head capsule; eye large, eye width greater than 1.5x greatest width of antennal scape. Anteromedial clypeal margin straight or slightly emarginate, median clypeal carinae not produced as teeth or denticles. Maximum number of mandibular teeth and denticles: three; mandibles (viewed from front) strap-like with inner and outer edges subparallel, striate, with piliferous punctures.

Alitrunk. Promesonotal sculpture present in form of uniform microreticulation with few mesopleural striolae; dorsal promesonotal face convex anteriad, otherwise flattened; erect and suberect promesonotal setae absent. Propodeal sculpture present as uniform microreticulation, with few or no striae or costulae; propodeal processes absent (propodeum smoothly rounded in profile or with slight hump at propodeal angle); lobes present as blunt flanges. Declivitous face of propodeum longitudinally concave between its lateral margins. Erect and suberect propodeal setae absent or very sparse; propodeal setulae absent. Propodeal spiracle lateral and about midway between metanotal groove and declivitous face of propodeum.

Petiole and postpetiole. Petiolar spiracle lateral and slightly anteriad of petiolar node. Petiolar node cuneate, dorsally rounded to cuneate, sharply tapered; sculpture present in form of microreticulation. Ratio of greatest node breadth (viewed from front) to greatest node width (viewed in profile) near 4:3. Anteroventral process always present as pronounced spur. Height ratio of petiole to postpetiole near 4:3. Sculpture present in form of microreticulation.

General characters. Colour either russet or brown with posterior promesonotum, propodeum, anterior sector of petiole, and apex of gaster more darkly infuscated, legs amber or uniformly fulvous. Worker caste monomorphic.

Etymology
Latin: “keeled”.

References based on Global Ant Biodiversity Informatics

 * Fisher J., L. Beames, B. J. Rangers, N. N. Rangers, J. Majer, and B. Heterick. 2014. Using ants to monitor changes within and surrounding the endangered Monsoon Vine Thickets of the tropical Dampier Peninsula, north Western Australia. Forest Ecology and Management 318: 7890.