Camponotus marcens

The brightly-coloured minor workers with a yellow-and-black gaster are most commonly encountered, often as they are running rapidly up and down Jarrah and Marri trunks. These ants will seek to evade detection by keeping to the opposite side of the tree to the side where the observer is standing. (Heterick 2009)

Identification
McArthur (2009) - Camponotus marcens has the sides of its head converging posteriorly in the minor worker whereas in Camponotus claripes the sides are parallel.

Distribution
Heterick (2009) - Seems to be confined to the Darling Range and southern wheatbelt (WA).

Distribution based on Regional Taxon Lists
Australasian Region: Australia.

Nomenclature

 *  marcens. Camponotus claripes subsp. marcens Forel, 1907h: 300 (s.w.) AUSTRALIA. Combination in C. (Myrmophyma): Emery, 1925b: 110. Raised to species: McArthur, 2009: 278.

Worker
Length 6.5 - 11.5mm. Worker major. Head more trapeze shaped with very weak convex sides, longer than broad, strongly edged behind. Eyes set nearer to the back. The basal surface of the propodeum is horizontal, and as long as the declining surface.The mandibles less curved. The whole ant is slimmer and the legs longer. Head almost dull. The sculpture is fine and much thicker and sharper than with the type. The coarse sculpture on the forehead is similar. Golden red; the fore part of the gaster is reddish yellow. Head and upper part of the gaster, apart from the yellow gold seam of the segments, dark brown. Antennae yellowish brown. Same as the type. Worker minor. Head behind narrower than in front, with convex border (the type it is wider than in front,with a concave border behind). Thorax is much less convex, longer. Eyes smaller. Reddish gold, mandibles and anterior border of the head yellow gold, posterior of the gaster brown; antennae bright brown. Otherwise same as the major.

McArthur (2009) - (Type material, MHNG): Major worker HW 2.85, HL 3.00, PW 1.90, FCW 1.0, HT 2.00, EL 0.55, TL 1.90. Minor worker HW 1.10, HL 1.60, PW 1.00, FCW 0.4, HT 0.90, EL 0.35, TL 1.70.

Major. Head sides posterior three quarters straight slightly tapering anteriorly, anterior quarter convex more strongly tapering anteriorly. Vertex nearly straight, in side view swollen. Clypeus anterior median third projecting forward, bounded by two blunt teeth, concave between. Mandibles with 6 teeth. Integument mainly glossy. Mesosoma in profile uniformly convex. Metanotum with two close transverse lines followed posteriorly by a short steep decline. Propodeum angle 135°, rounded. PD / D ~ 1.5. Petiolar node summit tending sharp. Erect setae on mesosoma dorsum sparse and scattered. Genae and underside of head with plentiful erect setae. Scape with plentiful short setae raised to 10° with a few erect. Tibiae with short setae raised to 10°. Colour: head and gaster reddish brown, mesosoma yellow brown.

Minor. Head sides straight tapering posteriorly. Vertex strongly convex. Clypeus anterior margin projecting anteriorly, feebly convex. Mandibles with 6 teeth. Integument mainly glossy. Mesosoma in profile uniformly weakly convex. Propodeal angle rounded. Petiolar node thick, length about half height, summit blunt. Erect setae on mesosoma dorsum sparse and scattered. Genae and underside of head with plentyful erect setae. Scape with plentiful short setae raised to 10° with a few erect. Tibiae with short setae raised to 10°. Colour: reddish yellow.

Type Material
Station 101, Mundaring Weir; Station 103, Guildford.

McArthur (2009) - 2 syntypes : 1 major and 1 minor worker “Forel Typus Hamburg SW Aust Exp 1905 Stat 101 Mundaring Weir 9.VII”.

References based on Global Ant Biodiversity Informatics

 * Heterick B. E. 2009. A guide to the ants of south-western Australia. Records of the Western Australian Museum Supplement 76: 1-206.
 * McArthur A. J. 2009. New species, new status and new synonymy for Camponotus from Australia (Hymenoptera: Formicidae). Myrmecological News 12: 273-286.