The only known collection of this species was made using pitfall traps. The specimens came from Kojonup, in the southern wheatbelt (WA).
This species has expanded, wing-like lateral extensions of the postpetiole. It is similar to Epopostruma mercurii but differs in that E. sowestensis has the petiolar spines indistinct and reduced to sharp angles while in E. mercurii these spines are well developed and distinct. In addition, E. sowestensis has distinct flanges connecting the bases of the propodeal spines and propodeal lobes while E. mercurii lacks these flanges.
Keys including this Species
Distribution based on Regional Taxon Lists
Distribution based on AntMaps
Distribution based on AntWeb specimens
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While Epopostruma can be fairly common they are often overlooked. Workers are slow-moving and most lie motionless when disturbed. Their nests are small, with up to about 100 workers, and are found in open soil or in soil under rocks, logs or small sticks. They also nest in cracks in large rocks. When nesting in open soil they are often found near the bases of trees. Tree-trunks are clearly an important substrate for foraging workers.
Almost all species forage at night although one species is known to occasionally forage on mallee stems during the day. They are also regularly found in leaf litter. Workers have been attracted to honey baits on trees in the late evening and at night. Their elongate and specialised mandibles form a type of snap-trap which is used to captured soft-bodied prey such as Collembola.
The following information is derived from Barry Bolton's New General Catalogue, a catalogue of the world's ants.
- sowestensis. Epopostruma sowestensis Shattuck, in Bolton, 2000: 58 (w.) AUSTRALIA.
- Holotype, worker, Kojonup, Western Australia, Australia, R.E & R.G., ANIC32-003773, Australian National Insect Collection.
Unless otherwise noted the text for the remainder of this section is reported from the publication that includes the original description.
In full face view the lateral margin of the head between the eye and the posterior corner generally angular. Pronotal spines present, short. Posterior section of metanotum in approximately the same plane as the dorsal face of propodeum, the junction of these plates either indistinct or in the form of a shallow trough or depression. Posterior face of propodeum with broad, distinct flanges which connect the bases of the spines to the propodeal lobes. Petiolar spines indistinct, reduced to sharp angles. Anterior face of postpetiole slightly longer than the dorsal face; sides of postpetiole expanded laterally in the form of thin, solid wings, their lateral margins flat; posterolateral margin of postpetiole (immediately anterior of gaster) weakly concave. Dorsum of petiole, postpetiole and gaster with straight or weakly curved erect hairs. First gastral tergite smooth. Body colour yellow-red; dorsal surface of head weakly infuscated; ventral regions of head, mandibles, antennae and legs slightly lighter; gaster uniform golden brown.
Holotype worker. TL 4.1mm, HL 0.85mm, HW 0.82mm, CI 96, MandL 0.45mm, MandI 53, SL 0.53mm, SI 65, PronW 0.50mm, ML 1.02mm.
- Heterick, B. E. 2009. A guide to the ants of South-western Australia. Records of the Western Australian Museum, Supplement 76:1-206. PDF
- Shattuck, S. O. 2000. Genus Colobostruma. Genus Mesostruma. Genus Epopostruma. Pp. 31-67 in: Bolton, B. The ant tribe Dacetini. Mem. Am. Entomol. Inst. 65: 1-1028 (page 63, worker, queen described)