Stereomyrmex anderseni

Taylor (1991) - The holotype was taken by pitfall trap in sclerophyll woodland on brown sand, dominated by Eucalyptus miniata and E. tetrodonta, with under-story of annual grasses (mostly Aristida sp.) and the leguminous scrub Bossiaea bossioides. Other ant genera present (identified by Andersen) included Rhytidoponera (4 spp.), Crematogaster (4 spp.), Meranoplus (5 spp.), Monomorium (6 spp.), Tetramorium (4 spp.), Iridomyrmex (6 spp.), Camponotus (5 spp.), and Polyrhachis (6 spp.). The most abundant species included Iridomyrmex sanguineus (Forel), Monomorium and Pheidole spp., and Paratrechina sp. aft. minutula Forel (A. N. Andersen pers comm.).

Identification
Taylor (1991) - S. anderseni is readily distinguished from Stereomyrmex dispar by its much smaller size, very different petiolar and postpetiolar structure, and pale colour.

Distribution based on Regional Taxon Lists
Australasian Region: Australia.

Nomenclature

 *  anderseni. Willowsiella anderseni Taylor, 1991a: 285, figs. 6-9 (w.) AUSTRALIA. Combination in Stereomyrmex: Bolton, 2003: 273.

Worker
TL ca. 2.0; HL 0.51; HW (across eyes) 0.46, (maximum behind eyes) 0.47; CI 92; SL 0.29; SI 62; PW 0.35; WL 0.58; midline length of petiolar node 0.14; petiolar node width 0.31; midline length of postpetiole 0.15; postpetiole width 0.33. Smaller than Stereomyrmex dispar, with different proportions. General features as in the accompanying figures.

Head expanded posterolaterally; anterior part of frons somewhat inflated; clypeus inflated anteromedially, median anterior border transverse, shallowly concave, abruptly reflexed ventrally and projecting forwards to slightly overhang the closed mandibles. Mandibles 5-toothed, apical tooth the largest and most acute, the others subequal in size, diminishing slightly from apex. Antennal club indistinctly 3-jointed, the two apical segments enlarged.

Pronotal shoulders narrowly rounded in dorsal view, semi-epaulate. Pronotum on each side with an obtuse ridge extending dorsally from its ventrolateral extremity to the shoulder, so that the anterolateral and lateral sections of the sclerite are more-or-less separated. Dorsum and sides of mesosoma lacking sutures, except for a short ventral section of the promesonotal suture on each side below the spiracle. Propodeal spines short but acute, posterodorsolaterally directed, slightly curved; each subtended by an anterodorsal carina, which defines the lateral margin of the propodeal dorsum; infradental lamellae small, rounded. Propodeal spiracle very small, situated near the middle of the relevant section of the lateral wall of the mesosoma.

Petiole and postpetiole as illustrated; the former much less bulky than in S. dispar, strongly transverse in dorsal view. Postpetiole similarly transverse, shorter at midline than petiole. Petiolar peduncle extremely short, slender; the spiracles minute, each surmounted by a strong angular process, which is clearly visible and approximately right-angular in dorsal view. Base of gaster quite deeply emarginate in dorsal view, closely reflecting posterior outline of postpetiole. Gaster somewhat broad and flattened, especially anteriorly; in side view more-or-less triangular, with apex anteriorly directed. Sting moderately strong, blade-like, without apical appendage.

Pilosity sparse; a few relatively long hairs on clypeus and mandibles, and on apex and underside of gaster; clypeus with a median and 2 lateral setae on anterior margin; shorter hairs sparse on underside of head. Fine pubescence everywhere moderately abundant. Sculpturing vaguely, densely foveolate on head, mesosoma and nodes; less distinct and more shining posteriad; overall somewhat reminiscent of some Crematogaster species. Gaster dorsally vaguely shagreened, dully shining. Colour bright yellow-brown; eyes black; mandibular teeth dark brown; gastral dorsum darkly infuscated, darkest medially.

Type Material
Western Australia: Kimberley District: King Edward River (15°08’50"S; 126°08’40"E). Holotype worker (1 June, 1988, A. N. Andersen). Deposited in (type number 7867). The holotype has been gold-palladium coated for scanning electron microscopy. It was unfortunately damaged in a laboratory accident, but its major parts are complete.



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.
 * Taylor, R. W. 1991. Notes on the ant genera Romblonella and Willowsiella, with comments on their affinities, and the first descriptions of Australian species (Hymenoptera: Formicidae: Myrmicinae). Psyche (Cambridge) 97: 281-296.