Colobostruma cerornata

This rare species is known from a limited number of collections scattered across Western Australia, South Australia and Victoria. So far it has only been found in heath habitats (Ants Down Under).

Identification
Shattuck (2000) - The only species in the genus with spatulate hairs on the head and which lacks wings on the lateral surfaces of the postpetiole, these surfaces being approximately vertical and rounding gradually from the dorsal surface to the ventral surface. It is also the only species with spongiform tissue on the petiole, postpetiole and gaster.

Key to Australian Colobostruma Species

Distribution based on Regional Taxon Lists
Australasian Region: Australia.

Biology
The following is modified from Brown (1959): The type locality (Dempster Head) is a large, rounded gneissic-outcrop hill with low heath-like shrubs and some dwarf wattles and mallee. Paratypes were taken at the type locality and on the sand plain about 8 km. northeast of the old (abandoned) Thomas River Station, about 65 miles east of Esperance, near the end of January, 1955. All specimens were taken at night by sweeping the low heath-like vegetation. This is one of a peculiar large-eyed, depigmented fauna of ants, including three species of Colobostruma, found foraging at night on low heath-like vegetation of the coastal plain of this isolated part of Western Australia.

Nomenclature

 *  cerornata. Colobostruma cerornata Brown, 1959c: 1, figs. 1, 2 (w.) AUSTRALIA. See also: Shattuck, in Bolton, 2000: 39.

Shattuck (2000) - This rare species is known from a limited amount of material collected in Western Australia, South Australia and Victoria. The single South Australian specimen is an ergatoid queen and thus differs significantly from other worker-based material currently available and it will not be considered further. The single Victorian specimen differs from the known Western Australian specimens in having fewer spatulate hairs on the dorsal surface of the head, weaker sculpture on the alitrunk and less well developed spongiform cuticle on the petiole, postpetiole and base of gaster. A case might be made for treating these specimens as belonging to separate taxa. However, the paucity of material and the large distance between them (over 1500 km.) would suggest caution in interpreting these morphological differences, especially given that they share many characters (such as eye size, head and mandible shape, sculpturing and body colour) and differ in relatively few.

Worker
Shattuck (2000) - TL 2.2 - 2.3, HL 0.53 - 0.54, HW 0.43 - 0.47, CI 81 - 87, ML 0.15 - 0.20, MI 28 - 38, SL 0.27 - 0.30, SI 57 - 70, PW 0.28 - 0.36, AL 0.58 - 0.63 (2 measured). Anterior region of head rounding gradually from the dorsal to lateral surfaces, not phragmotic. In full-face view ridge immediately in front of eye weakly concave. Frontal lobes and lateral margins of clypeus smooth relative to the surrounding surface of the head. Eyes unusually large. Mandibles narrow, elongate. Hairs present on dorsum of head, spatulate. Posterior margin of head broadly concave. Antenna with 4 segments, the scape gently curved and without a subbasal lobe. In dorsal view the widest point of the pronotum is at the humeral angles. Propodeum high, its posterior face slightly less than the height of the petiolar node and with broad, thin lamellae; in profile the dorsum of the alitrunk broadly convex, the metanotal groove shallow but present. Lateral postpetiole with its sides approximately vertical, not expanded outwards. Sides of petiole, postpetiole and base of gaster with spongiform cuticle, the amount varying from extensive (in Western Australian specimens) to slight (in the Victorian specimen). First gastral tergite smooth, superimposed with low carinae on the anterior one-third. Body colour uniform yellow.

Type Material
Shattuck (2000) - Holotype and paratype workers, AUSTRALIA: Western Australia, Esperance, Dempster Head (= Telegraph Hill), 4-6.ii.1955 (E.O. Wilson); paratype workers, Western Australia, 65 miles E of Esperance, Thomas River Station, i.1955 (E. O. Wilson & C.P. Haskins) [examined].

Additional References

 * 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.