Dolichoderus reflexus

Dolichoderus reflexus is a mallee woodland species that nests in soil with craters at their entrances. It is widespread across much of southern Australia but is nowhere common. Workers forage on low vegetation. While most records are from western localities, there are two records, collected a year apart, from south-eastern Queensland, some 850kms from the next closest record.

Identification
Pale markings absent from lower margin of the eyes; pronotum and propodeum lacking spines; in dorsal view the pronotum with strongly developed shoulders, with the area between the shoulders weakly convex to weakly concave; dorsum of propodeum highly arched and often with flat or even weakly concave sections; posterior face of propodeum, deeply concave often nearly semicircular; separated from the dorsal face by a distinct carina; gaster with sparse pubescence on the first gastral tergite and hairs generally not overlapping or entirely absent; tibiae with erect or suberect hairs.

This species is morphologically similar to Dolichoderus nigricornis and some individual can be difficult to separate. This is especially the case where the dorsal face of the propodeum is relatively low and the posterior face relatively shallow. However, in these cases, especially for specimens from South Australia, the humeral angles are much stronger in this species while they are more rounded and less angular in D. nigricornis.

Distribution based on Regional Taxon Lists
Australasian Region: Australia.

Nomenclature

 *  reflexus. Dolichoderus (Hypoclinea) reflexus Clark, 1930b: 261, fig. 13 (w.) AUSTRALIA. Senior synonym of armstrongi: Shattuck & Marsden, 2013: 130.
 * armstrongi. Dolichoderus (Hypoclinea) armstrongi McAreavey, 1949: 17, figs. 48, 49 (w.) AUSTRALIA. Junior synonym of reflexus: Shattuck & Marsden, 2013: 130.

Description
Humeral angles more pronounced in eastern material, less so in Western Australian material. Dorsal propodeal surface varying from angular with flat anterior and flat to weakly concave posterior sections to evenly convex. Petiolar node varying from relatively thin with a distinctly angular dorsum and weakly sculptured to relatively thick with a broadly rounded dorsum and heavily sculptured. Head always dark, body generally yellow-red, but sometimes dark red-brown and similar in colour to head. Gaster ranging from yellowish-red to red-black.

Measurements (n=5). CI 84–91; EI 27–32; EL 0.23–0.27; HL 0.85–1.02; HW 0.71–0.91; ML 1.08–1.43; MTL 0.56–0.68; PronI 76.66–81.26; PronW 0.56–0.74; SI 103–113; SL 0.80–0.94.

This widespread species shows variation in a number of characters. The humeral angles are more pronounced in eastern material and less so in Western Australian material. The curvature of the dorsal propodeal surface varies from angular with flat anterior and flat to weakly concave posterior sections to evenly convex. However no obvious geographic pattern was detected for this variation and it appears to be intraspecific.

Based on gaster colour specimens can largely be divided into pale forms and dark forms. However, while dark forms are always distinct, the pale forms show considerable variation and some individuals approach the colour found in dark forms; no geographic pattern was found with all colour forms found in all areas. Additionally, the size and sculpturing pattern of the petiolar node varies considerably. In some specimens the node is relatively thin, with a distinctly angular dorsum and weak sculpturing. In other individuals the node is relatively thick with a broadly rounded dorsum and heavy sculpturing. As with the last character, no geographic pattern was noted and all forms occur in all regions. Even the type series of D. armstrongi has workers with both types of petiole, strongly suggesting that this variation is intraspecific rather than interspecific. Taken together, the variation in these characters is interpreted as supporting a single widespread and slightly variable species. However, it should be noted that there are relatively few specimens available for study, especially given the broad geographic range of this taxon, and this conclusions drawn here should be re-examined as additional material becomes available.

Additional References

 * Shattuck, S.O. & Marsden, S. 2013. Australian species of the ant genus Dolichoderus (Hymenoptera: Formicidae). Zootaxa 3716, 101–143 (doi 10.11646/zootaxa.3716.2.1).