Dolichoderus formosus

Dolichoderus formosus occurs in two distinct regions, one in south-western Western Australia, the other in south-central coastal South Australia. It is found in mallee and scrub habitats and nests under rocks.

Identification
Pale markings absent from lower margin of the eyes; head dark brown to black and similar in colour to gaster; sculpturing pattern of head and pronotum, with large but shallow and closely spaced foveae; in dorsal view the pronotum with only weakly defined shoulders, with the area between the shoulders more strongly convex to flat; pronotum and propodeum lacking spines; dorsum of propodeum weakly and evenly convex, the length shorter (at most approximately the same length) than the posterior face, with a narrow carina separating the dorsal and posterior faces; posterior face of propodeum weakly concave, separated from the dorsal face by a distinct carina; mesosoma with erect hairs but few to no appresssed pubescence; gaster dark brown to black with little or no pubescence; tibiae with erect or suberect hairs.

Dolichoderus formosus is similar to Dolichoderus canopus, but is distinguishable by the large, shallow and closely spaced foveae on the dorsum of the head and pronotum, which are distinctly striate on the lateral pronotum. This species most closely resembles Dolichoderus nigricornis but can be distinguished by having the head colour similar to the gaster (dark brown to black) compared to the lighter coloured head (reddish to reddish-brown) and dark gaster (dark brown to black) in D. nigricornis, and in lacking appressed pubescence from the mesosoma and gaster.

Identification Keys including this Taxon

 * Key to Australian Dolichoderus Species

Distribution based on Regional Taxon Lists
Australasian Region: Australia.

Nomenclature

 *  formosus. Dolichoderus (Hypoclinea) formosus Clark, 1930b: 265, fig. 15 (w.q.) AUSTRALIA. Senior synonym of occidentalis: Shattuck & Marsden, 2013: 119.
 * occidentalis. Dolichoderus (Hypoclinea) occidentalis Clark, 1930b: 268, fig. 12 (w.) AUSTRALIA. Junior synonym of formosus: Shattuck & Marsden, 2013: 119.

Worker
Head and gaster black, mandibles and thorax red, antennae and legs brown, or reddish brown. On a few examples the head is blackish brown, the clypeus lighter.

Subopaque. Coxae, node and gaster smooth and shining. Head coarsely punctate and finely reticulate. Clypeus finely longitudinally striate. Thorax punctate-rugose and finely reticulate.

Hair yellow, erect, rather short, but abundant throughout, suberect on the antennae and legs. Pubescence not apparent.

Head longer than broad, as broad behind as in front, the occipital border feebly, the sides strongly, convex. Frontal carinae as long as their distance apart. Clypeus convex above, the anterior border convex, with a deeply excised concavity in the middle. Eyes large, convex, placed at the middle of the sides. Scapes extending beyond the occipital border by barely one-third of their length; first segment of the funiculus one-tenth longer than the second, the other subequal. Masticatory border of the mandibles feebly denticulate, terminal border with nine or ten strong sharp teeth. Thorax twice as long as broad. Pronotum one and two-third times broader than long, convex in front, the angles bluntly rounded, depressed, or feebly concave longitudinally above. Epinotum one and one-third times longer than broad, the posterior border convex; in profile strongly convex longitudinally, one-third longer than the declivity, the latter strongly concave. Node slender, three times as broad as long, the dorsum convex; in profile both faces convex toward the top, the latter bluntly pointed. Gaster longer than broad, feebly concave in front below. Legs robust.

Shattuck and Marsden (2013) - Body colour varying from red to black with mandibles, antennae and legs varying from reddish-brown to brown. Sculpturing ranging from smooth and shiny to weakly matte.

Measurements (n=5). CI 78–84; EI 28–32; EL 0.25–0.27; HL 1.05–1.15; HW 0.84–0.95; ML 1.43–1.60; MTL 0.76–0.86; PronI 70.85–76.37; PronW 0.59–0.70; SI 112–123; SL 1.02–1.11.

Queen
Similar to the worker, but much larger and winged. The colour is brighter. On the mesonotum there is a large black spot on the anterior margin and an elongate black spot on each side near the middle. The scutellum is smooth and shining, the gaster very finely and densely punctate. Wings missing.

References based on Global Ant Biodiversity Informatics

 * Shattuck S. O. 1994. Taxonomic catalog of the ant subfamilies Aneuretinae and Dolichoderinae (Hymenoptera: Formicidae). University of California Publications in Entomology 112: i-xix, 1-241.
 * Shattuck S. O., and S. Marsden. 2013. Australian species of the ant genus Dolichoderus (Hymenoptera: Formicidae). Zootaxa 3716(2): 101-143.