Camponotus prostans

Mainly confined to the south-west and southern portions of the SWBP, but has been recorded as far afield as the Gibson Nature Reserve, well to the NE of the SWBP.

Identification
Camponotus prostans and Camponotus dryandrae are very difficult to separate on morphological characters alone. The only reliable feature is the reduced number of setae found on the venter of the head capsule in C. prostans, a feature that requires examination through a microscope. However, in the field their rich reddish- or yellowish-brown-and-black colouration separates most workers of C. dryandrae from the more sober, uniformly blackish or brown-and-black C. prostans.

McArthur and Adams (1996) - Camponotus prostans possesses a few setae on the gula, and is distinguished from Western Australian Camponotus longideclivis and eastern Australian Camponotus consobrinus by the absence of seta on the gula in the latter two species. In dorsal view, the heads of the largest major workers in C. prostans appear circular, as a consequence of HW being greater than HL.

Distribution based on Regional Taxon Lists
Australasian Region: Australia.

Biology
Farhan Bokhari noted an interesting behaviour of these ants. He observed a few workers guarding a nearby Iridomyrmex conifer nest mound, made of sticks and stones, and attacking any Iridomyrmex workers that came out. The larger Camponotus would grab the smaller day-active Iridomyrmex in their mandibles and proceed to spray formic acid on them from their acidopores. The Iridomyrmex workers would then die in a few seconds. It is presumed this behaviour serves to suppress competition and allows these ants more time to forage.

Nomenclature

 *  prostans. Camponotus nigriceps subsp. prostans Forel, 1910b: 72 (w.q.) AUSTRALIA. [First available use of Camponotus nigriceps subsp. obnigra var. prostans Forel, 1907h: 301; unavailable name.] Junior synonym of lividipes: Wheeler, W.M. 1933b: 23; Clark, 1934c: 71. Revived from synonymy and raised to species: Taylor, 1987: 14; McArthur & Adams, 1996: 40.

Worker
Length. 6.8-10.5 mm. Smaller than the subspecies obniger coming from South Australia, quite black or brownish black with pale yellow legs; mandibles, clypeus and flagellum brownish red. Somewhat more glossy than the sub species type and with somewhat longer and richer pubescence especially on the limbs.

McArthur and Adams (1996) - Colour: head black to dark brown; mesosoma colour ranges from black all over to reddish brown all over, some specimens with combinations of above colours; legs lighter, often yellowish; posterior gaster black or dark brown, anterior gaster colour similar to posterior gaster or like most of mesosoma. Pilosity: up to 0.5 mm long plentiful on pronotum and mesonotum with 2-8 on or propodeum (Fig · 31a,b), sparse and shorter on gula sometimes obsolete, plentiful on gaster pointing backwards, short setae on scapes raised to 30°, short setae on midtibiae 20-40°. Pubescence: a coat of suberect setae about 0.1 mm long, spaced < length, usually whitish, visible with transmitted light on the dorsum of mesosoma; adpressed and sparse on head. Integument finely reticulate, glossy. Node summit viewed from rear: conkvex or flat in major workers, convex in other workers. Metanotum usually distinct in major workers.

HW = 1.80-3.5 mm; HL = 2.30-3.45 mm; TL = 2·60-3.00 mm; n = 20. TL = 1.89 + 2.22 log HW (n = 11, r = 0.95, s.e.(y) = 0.17, s.e.(x) = 0.04). PD:D = 2.0 in major workers increasing to 3.0 in minor workers. HW:HL = often reaches 1.05 in major workers where HW > 3.4 mm.

Queen
Length. 15-17 mm. Same color as the worker. Pubescence more ample than the type. Wings weak somewhat stockier in proportion than the type.The clypeus has the exact form of the type. The worker from Lion Mill has above all more upstanding hair and also much stronger spines on the legs.

Etymology
McArthur and Adams (1996) - Presumed from porost (Latin: outstanding) as the colour of the subspecies type is much darker than that of the type, C. nigriceps.

References based on Global Ant Biodiversity Informatics

 * Gunawardene N.R. and J.D. Majer. 2004. Ants of the southern Carnarvon Basin, Western Australia: an investigation into patterns of association. Records of the Western Australian Museum 22: 219-239.
 * McArthur A. J., and M. Adams. 1996. A morphological and molecular revision of the Camponotus nigriceps group (Hymenoptera: Formicidae) from Australia. Invertebr. Taxon. 10: 1-46.