Monomorium arenarium

This species has been found in sandy areas at Swanbourne (Perth metropolitan area), Eneabba, Esperance and Nornalup in the SWBP, as well as in SA and Tas.

Identification
Heterick (2001) - This distinctive little Monomorium has a wide distribution, with an apparent predilection for sandy coastal soil and dry sclerophyll woodland. However, several collections have been made away from the coast. The oblique, sloping propodeum is sufficient to distinguish it from other small, yellow Monomorium. The queen also is distinctive, the oblique propodeal declivity being unlike that of other small Australian Monomorium queens.

Heterick (2009) - A small, orange ant whose queens have an unusual appearance

Distribution based on Regional Taxon Lists
Australasian Region: Australia.

Nomenclature

 *  arenarium. Monomorium arenarium Heterick, 2001: 396, figs. 34, 135, 144, 152, 177 (w.q.) AUSTRALIA.

Worker
Holotype. HML 1.30; HL 0.45; HW 0.41; Cel 92; SL 0.41; SI 81; PW 0.25. Others. HML 1.25-1.49; HL 0.46-0.55; HW 0.36-0.47; Cel 79-90; SL 0.30-0.42; SI 68-90; PW 0.24-0.28 (19 measured, including alcohol specimens from Swanboume ).

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

Head. Frons of head capsule smooth and shining with evenly spaced, appressed setulae, or smooth and shining with incurved decumbent and subdecumbent setulae. (Viewed from front) compound eyes set in anterior half of head capsule. Venter of head capsule without elongate, basket-shaped setae. Maximum number of mandibular teeth and denticles: three.

Alitrunk. Dorsal promesonotal face convex anteriad, otherwise flattened; erect and suberect promesonotal setae absent. Propodeal sculpture present as faint microreticulation with few striae, mainly on lower lateral surface; dorsal propodeal face sloping posteriad, with wedge-shaped flattening or shallow depression that is widest between propodeal angles; processes absent (propodeum smoothly rounded in profile or with slight hump at propodeal angle), or present on posterior propodeal angles in form of B. E. Heterick minute lamellae; lobes present as blunt flanges. Declivitous face of propodeum flat. Erect and suberect propodeal setae absent or very sparse. Propodeal spiracle lateral and about midway between metanotal groove and declivitous face of propodeum.

Petiole and postpetiole. Petiolar node conical, dorsally rounded; sculpture absent, petiolar node smooth and shining. Anteroventral process present as pronounced spur, or slender carina that tapers posteriad. Ventral lobe present in some individuals. Height ratio of petiole to postpetiole near 4:3. Ventral process present and distinct.

Gaster. Pilosity of first gastral tergite consisting mainly of decumbent and subdecumbent setulae.

General characters. Colour orange, or light tawny yellow. Worker caste monomorphic.

Queen
HML 1.98-2.37; HL 0.62-0.68; HW 0.57-0.60; Cei 86-93; SL 0.48-0.53; SI 84-88; PW 0.44-0.53 (4 measured).

Head. Head trapezoid, narrowest at the vertex; frons smooth and shining with incurved decumbent and subdecumbent setulae.

Alitrunk. Propodeal sculpture absent; propodeum smooth and shining; dorsal propodeal face gently convex. Metapleural lobes present as blunt flanges. Propodeal spiracle lateral and about midway between metanotal groove and declivitous face of propodeum.

Petiole and postpetiole. Ratio of greatest node breadth (viewed from front) to greatest node width (viewed in profile) near 1: 1 to near 3:4. Anteroventral process present as a broad flange along the underside of the petiole. Height ratio of petiole to postpetiole near 1:1 to near 4:3; height-length ratio of postpetiole near 3: 1 to near 2: 1. Ventral process present and distinct.

Gaster. Pilosity of first gastral tergite consisting mainly of decumbent and subdecumbent setulae.

General characters. Colour amber, often darker on dorsal surfaces. Brachypterous alates not seen. Ergatoid or worker-female intercastes not seen.

Type Material
Holotype. Worker, South Australia, Belair, 13-17.i.1972, P. J. M. Greenslade, trap 3. Paratypes. South Australia: 1 Worker, Belair, iv.1971, traps (ANIC); 2 queens, Black Oak Ck., Koonamore, 15.iv.1973, P. J. M. Greenslade (ANIC); l queen, Koonamore, iv.1973, P. J. M. Greenslade, pitfall traps ; I queen, 2 workers, Natl Pk, Lofty Ra., 23.iii.1969, dry sclerophyll, ridge 1800 ft, nest in hard soil, ANIC ants vial 66-74 (BMNH). Tasmania: 3 workers, Greens Beach, 22.xii.1990, B. B. Lowery, dry sclerophyll, under rock, reg. n. 12:5601, rare (QVMT). Western Australia: 4 workers, Esperance, 2.i.1970, B. B. Lowery, coastal sand heath, nest in sand near road, 7 pm, long trail between craters ; 1 worker, Nornalup, 18.xii.1969, B. B. Lowery, wet sclera., in soil (MCZ); 1 worker, Swanbourne, 19.vii.l987, B. E. Heterick, soil, mixed native/exotic veg., vegetated coastal dune, 266/6MonBH46.



Etymology
Latin: “of sand/sandy”.