Monomorium aithoderum

Little is known of M. aithoderum’s biology. One worker was collected on Conostylis (“trigger plant”).

Identification
Heterick (2001) - Monomorium aithoderum is a small, inconspicuous species. Nearly all specimens have come from Western Australia, but the ant may have a much broader range, as the recent collection of material in the Eyre Peninsula demonstrates. This ant is not easily separated from other tiny Monomorium with a reticulate propodeum, but it is never yellow (unlike Monomorium micula and many Monomorium sydneyense specimens), has a more elongate promesonotum and a more compressed propodeum than brown samples of M. sydneyense, and has an oval eye (unlike Monomorium stictonotum and Monomorium nanum).

Heterick (2009) - Monomorium aithoderum, Monomorium nanum and Monomorium stictonotum are minute, nondescript orange or brownish species of very similar appearance that make up much of the Monomorium biomass in drier areas of southern Australia.

Distribution based on Regional Taxon Lists
Australasian Region: Australia.

Nomenclature

 *  aithoderum. Monomorium aithoderum Heterick, 2001: 394, figs. 32, 131 (w.) AUSTRALIA.

Worker
Holotype. HML 1.20; HL 0.48; HW 0.41; Cei 84; SL 0.36; SI 89; PW 0.26. Others. HML 1.07-1.52; HL 0.46-0.57; HW 0.40--0.48; Cei 78-91; SL 0.34-0.40; SI 80-89; PW 0.23-0.30 (16 workers).

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

Head. (Viewed from front) compound eyes set at midpoint of each side of head capsule; (viewed laterally) compound eyes set posterior of midline of head capsule; eye moderate, eye width 0.5-1.5x greatest width of antennal scape. Anteromedial clypeal margin emarginate, median clypeal carinae produced apically as pair of pronounced teeth. Mandibles (viewed from front) strap-like with inner and outer edges subparallel, striate, with piliferous punctures; basal tooth not enlarged.

Alitrunk. Promesonotal sculpture present in form of microreticulation, striolae and striae on the mesopleuron, and striolae on posterodorsal promesonotal surface; dorsal promesonotal face evenly convex; erect and suberect promesonotal setae absent, or greater than 10. Metanotal groove present as feebly impressed furrow between promesonotum and propodeum, or present as distinct and deeply impressed trough between promesonotum and propodeum. Propodeal sculpture present as uniform microreticulation, with few or no striae or costulae. Declivitous face of propodeum longitudinally concave between its lateral margins. Erect and suberect propodeal setae absent or very sparse, or 5-10 setae present; propodeal setulae appressed.

Petiole and postpetiole. Petiolar node cuneate, dorsally rounded; sculpture absent, petiolar node smooth and shining to present in form of microreticulation. Ratio of greatest node breadth (viewed from front) to greatest node width (viewed in profile) near 4:3. Height ratio of petiole to postpetiole near 4:3. Sculpture absent on dorsum, at least: postpetiole smooth and shining.

General characters. Colour tawny orange (head may be darker than alitrunk when viewed from front), mandibles conspicuously yellow in some specimens, gaster and legs light brown to brown. Worker caste monomorphic.

Etymology
Greek: “burnt, fiery red color” + “skin or hide”.