Dolichoderus omicron, Shattuck, Steven O. & Marsden, Sharon, 2013

Shattuck, Steven O. & Marsden, Sharon, 2013, Australian species of the ant genus Dolichoderus (Hymenoptera: Formicidae), Zootaxa 3716 (2), pp. 101-143 : 127-129

Dolichoderus omicron sp. n.

( Fig. 18 )

Types. Holotype worker from Poochera, "Freightline site" just south of village, 32°43'S 134°50'E, South Australia, 10–13 November 1981, R.W. Taylor & R.J. Bartell, nocturnal foragers, mallee woodland (ANIC, ANIC32- 066601); 5 paratype workers, same data as holotype except ANIC32- 061292 (ANIC); 6 paratype workers from Poochera, "Rubbish dump site" just north of village, 32°43'S 134°50'E, South Australia, 10–13 November 1981, R.W. Taylor & R.J. Bartell, diurnal collection, mallee woodland (ANIC32- 061295, 3 in ANIC, 3 in MCZC); 1 paratype worker from the Poochera area, " Nothomyrmecia original site", 32°43'S 134°50'E, South Australia, 13–17 November 1977, R.W. Taylor & P.S. Ward, diurnal (ANIC, ANIC32- 061294); 2 paratype workers from Poochera, "collected in CSIRO enclosure", 32°43'S 134°50'E, South Australia, October–November, 1984, R.W. Taylor & R.J.

Bartell, mallee woodland (ANIC, ANIC32- 061291); 1 paratype worker from Poochera, site "X" 2km S of village, 32°43'S 134°50'E, South Australia, 6–15 November 1982, R.W. Taylor & R.J. Bartell, mallee woodland (ANIC, ANIC32- 061293).

Diagnosis. Pale markings absent from lower margin of the eyes; pronotum and propodeum lacking spines; in dorsal view the pronotum with only weakly defined shoulders, with the area between the shoulders more strongly convex to flat; 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; gaster yellowish red and lighter in colour than the mesosoma; 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 most similar to D. canopus but can be distinguished by having a gaster yellowish red and lighter in colour that the mesosoma whereas D. canopus has a gaster which is at least similar in colour if not darker than the mesosoma.

Worker description. See Fig. 18 . Available specimens uniform and similar to the figured individual except in showing moderate variation in body colour, which varies from light reddish-brown to brown (as illustrated), and leg colour, which ranges from yellow-red to reddish-brown (as illustrated).

Measurements (n=5). CI 82–87; EI 31–34; EL 0.24–0.28; HL 0.87–0.99; HW 0.72–0.86; ML 1.14–1.34; MTL 0.61–0.71; PronI 66.49–70.16; PronW 0.49–0.59; SI 112–119; SL 0.85–0.96.

Material examined. New South Wales: 7mi. S Hillston (Lowery,B.B.) (ANIC); Bogan River (Armstrong,J.) (ANIC); South Australia: 10km S Yardea HS, Gawler Ranges (Greenslade,P.J.M.) (ANIC); 11mi. E Kimba (Greenslade,P.J.M.) (ANIC); 53km E Vokes Hill, Victoria Desert (Greenslade,P.J.M.) (ANIC); Blyth (Lowery,B.B.) (ANIC); Brookfield [Brookfield Conservation Park] (Greenslade,P.J.M.) (ANIC); Cambrai (Greenslade,P.J.M.) (ANIC); Ferries-McDonald Reserve, Monarto Sth. [Monarto South] (Greenslade,P.J.M.) (ANIC); Goondooloo (Crozier,R.C.) (ANIC); Inkster, SW Poochera (Casparson,K.) (ANIC); Mambray Creek, S Flinders Ranges (Greenslade,P.J.M.) (ANIC); Monarto Stn (Greenslade,P.J.M.) (ANIC); Poochera (Taylor,R.W. & Bartell,R.J.) (ANIC); Poochera area (Taylor,R. & Ward,P.) (ANIC); Sevenhill (Lowery,B.B.) (ANIC); Sinclair Gap (Barker,S.) (SAMA); Streaky Bay (Lowery,B.B.) (ANIC); Victoria: Wyperfeld National Park., Duttuck Tk. (Harvey,M.S. & Roberts,B.E.) (ANIC); Western Australia: 11 mi. E Pingrup (Greaves,T.) (ANIC); 19mi. NNW Widgiemooltha (Taylor,R.W.) (ANIC); 26mi. ENE Norseman (Taylor,R.W.) (ANIC); 3km S Wundowie (Ward,P.S.) (ANIC); Caiguna (Lowery,B.B.) (ANIC); Eucla (Shattuck,S.O.) (ANIC); York (Douglas,A.M. & Douglas,M.J.) (ANIC).

Comments. Dolichoderus omicron is found in semi-arid open forested areas such as mallee woodlands and broombrush thickets across most of southern Australia. It forages during the day in columns primarily on the ground and nests in soil under rocks.

Figures

FIGURE 18. Dolichoderus omicron, worker from Eucla, Western Australia (ANIC 32 - 063771). A. Front of head; B. Side of body; C. Top of body; D. Distribution of material examined.