Diacamma colosseense

This species is allopatric to other species of Diacamma, occurring along the south-eastern coast of Queensland from just north of Rockhampton south to Bundaberg.

Identification
Anterior clypeal margin broadly rounded medially. Anterior region of mandible mainly smooth, basal region weakly striate, elongate foveae along entire length. Larger body size (compare head length, head width, mesosomal length, mid-tibial length and scape length). Dorsal surfaces of pronotum and head with distinct rugae. Petiolar spines relatively narrowly spaced, anterior and dorsal faces of node similar in length and separated by a broad, rounded angle.

Diacamma colosseense is most similar to Diacamma schoedli. It differs in being larger, in having weaker mandibular sculpturing and having the anterior clypeal margin broadly rounded medially (it is more angular in Diacamma schoedli). It differs from Diacamma australe in the shape of the petiolar spines, shape of the node and sculpturing on the first gastral segment as outlined above under that species.

Identification Keys including this Taxon
Key to Australian Diacamma Species

Distribution based on Regional Taxon Lists
Australasian Region: Australia.

Nomenclature

 *  colosseense. Diacamma australe var. colosseensis Forel, 1915b: 26 (w.) AUSTRALIA. Junior synonym of australe: Taylor & Brown, D.R. 1985: 29. Revived from synonymy and raised to species: Shattuck & Barnett, 2006: 15.

Taxonomic Notes
Forel (1915) described D. australe colosseense based on syntypes from Colosseum, Chillagoe, Atherton, and Gin Gin, Queensland. Shattuck (2006) examined three specimens (on a single pin) from Gin Gin and a single specimen from Atherton located in the Muséum d'Histoire Naturelle, Geneva. The Gin Gin specimens, which were in good condition, differed from the Atherton specimen and represent a separate species. These specimens match the concept of D. colosseense proposed by Shattuck (2006) and one was designated the lectotype for the name.

The single Atherton specimen (which is in poor condition) is consistent with Forel's original description in the shape of the node, the only character mentioned in detail. This shape clearly applies to Diacamma australe. Additional examination of this specimen shows that it shares a range of characters with D. australe, including the shape of the petiolar spines and sculpturing on the first gastral tergite. Based on these similarities this specimen is treated by Shattuck (2006) as conspecific with Fabricius' D. australe. With the lectotype designation for D. colosseense this specimen becomes a secondary type (a paralectotype) and therefore does not provide a name for these taxa.

Description
Measurements (n = 8): HL 2.82 - 3.05 mm, HW 2.23 - 2.62 mm, CI 79 - 86, SL 3.22 - 3.47 mm, SI 130 - 146, ML 4.20 - 4.41 mm, MTL 2.65 - 2.86 mm, PH 1.61 - 1.78 mm, PL 1.02 - 1.15 mm, PI 62 - 67.