Camponotus scratius

Very small, minor workers of C. scratius are among the smallest Camponotus in Australia (Heterick 2009).

Identification
Heterick (2009) - Camponotus scratius and Camponotus insipidus (as C. minimus) are both common, and, being very similar in appearance, are easily confused. Both major and minor workers, however, can be distinguished by the presence (C. scratius) or absence (C. insipidus) of setae on the venter of the head capsule.

Distribution
Heterick (2009) - Wide range in coastal WA. In the lower south-west, C. insipidus (as C. claripes minimus) is found in both coastal and inland regions.

Distribution based on Regional Taxon Lists
Australasian Region: Australia.

Nomenclature

 * . Camponotus scratius Forel, 1907h: 304 (s.w.q.) AUSTRALIA (Western Australia).
 * Combination in C. (Myrmophyma): Forel, 1914a: 269;
 * combination in C. (Thlipsepinotus): Santschi, 1928e: 483.
 * Status as species: Emery, 1925b: 112; Taylor & Brown, 1985: 119; Taylor, 1987a: 14; Bolton, 1995b: 123; McArthur, 2007a: 333; Heterick, 2009: 68; McArthur, 2010: 76; McArthur, 2014: 58.
 * Current subspecies: nominal plus nuntius.
 * samueli. Camponotus samueli McArthur, 2008: 124, figs. (w.) AUSTRALIA (South Australia, Northern Territory).
 * Status as species: McArthur, 2010: 74; McArthur, 2014: 58.
 * Junior synonym of scratius: Heterick, 2021: 17.

Description
Worker major. Length 5.3-6.5 mm.. Mandibles 7 teeth, rather weakly curved, very finely and thickly punctate reticulate, with many scattered shallow punctations; they are big with moderately convex outer edge. Clypeus anterior with a narrow, half rectangular, half arc-shaped anterior edge; in the middle posterior with a feeble carina. Frontal area diamond shaped. Frontal carinae very strongly divergent. Head somewhat broader than long, posterior wider than anterior, with very strong convex sides, posterior somewhat gently rounded. Eyes flat. The scape not quite or scarcely reaches the posterior border. Mesometanotal suture not sharp. Pronotum not margined; but the whole dorsum of the thorax somewhat flattened, only weakly domed transversely as well as longitudinally, viewed from above similar to michaelseni, almost like an isosceles triangle. Yet the triangle has no apex, as the basal surface of the metanotum (= propodeum) possesses a short posterior edge. Sloping surface, steep, high, but still shorter than the base surface and the mesonotum taken together, joining into the base surface by a short sharp curve. Node thin, rather wide, above sharp edged. Gaster very big, anterior vertical. Thighs somewhat thickened towards the base; limbs short.

Sculpture and pilosity as with michaelseni, but the flat lying hair covering, although very short and scattered is more distinct on the body and more upstanding hair on the clypeus. Brown; Mandibles, cheeks, anterior border of the clypeus and tarses reddish. Posterior edge of the gaster and legs bright yellow, antennae reddish yellow. Often the head and thorax are yellow brown or brown yellow. Worker minor. Length 2.8-3.1 mm. Mandibles glossy,but narrower and more weakly punctate, clypeus very strongly projecting arc shaped anterior lobe, weakly carined in the middle. Head long rectangular, a good 1.25times longer than wide, posterior somewhat wider than anterior, with only weakly convex sides. Posterior edge very weakly convex. Eyes big and rather flat. The scape protrudes over the posterior border of the head by over 1/3 of its length. Thorax similar to the worker major, but the metanotum (= pronotum) is much narrower, almost blunt, and forms from front to back a single strong convex curve, without a boundary between the basal surface and the declivity. Everything else is similar to the major worker, but the antennae, the tarses and almost all the anterior half of the head yellow, the rest of the limbs pale yellow. Sometimes head and thorax are partly or completely brownish yellow. Queen. Length 7.5 mm. Similar to the worker major, but head is more trapeze shaped. The scape exactly protrudes over the posterior border of the head. Basal surface of the metanotum (= pronotum)very short scarcely half as long as the declivity, rather sharply separated from it. Node thin, with sharp, summit pointed. Wings almost water bright, lightly tinted with brown, with bright brown ribs and edges. Almost everything is similar to the worker major. Station 114, Buckland Hill; Station 118, Fremantle, Kirchhof.

This small species is really odd, the difference between the minor and major worker is most distinct. Transition forms between the two have not been collected.

References based on Global Ant Biodiversity Informatics

 * Bisevac L., and J. D. Majer. 1999. Comparative study of ant communities of rehabilitated mineral sand mines and heathland, Western Australia. Restoration Ecology 7(2): 117-126.
 * Heterick B. E. 2009. A guide to the ants of south-western Australia. Records of the Western Australian Museum Supplement 76: 1-206.
 * Majer J. D., S. K. Callan, K. Edwards, N. R. Gunawardene, and C. K. Taylor. 2013. Baseline survey of the terrestrial invertebrate fauna of Barrow Island. Records of the Western Australian Museum Supplement 83: 13-112.
 * McArthur A. J. 2008. New species of Camponotus (Insecta: Hymenoptera: Formicidae) from Australia. Annalen des Naturhistorischen Museums in Wien. B, Botanik, Zoologie 109: 111-129.