Camponotus humilior

A member of the Camponotus maculatus group. Members of this group share the following biological attributes: (a) mostly nocturnal, (b) nests are in clay soil, never in sand, (c) entrances to nests are well hidden, (c) strong attraction to honey bait at night, (d) domination. (McArthur and Leys 2006)

Identification
McArthur and Leys (2006) - Camponotus maculatus group species share the following distinguishing characters: 1. The most striking character is the distinct occipital carina in minor workers (see the dorsal head view of the minor worker in the caste images of Camponotus crozieri). This forms a ridge externally and probably serves to strengthen the anterior parts of the head (Snodgrass 1935), it is absent in major workers. 2. Strong dimorphism, i.e., workers encountered are mostly either major or minor, medium workers are non existent or very scarce. 3. The sides of the heads of major workers taper strongly to the front (Fig. 2) while in minor workers, the sides are mostly parallel and taper to the rear. 4. The vertex in major workers is concave or flat, in minor workers it is convex. 5. The scape and tibiae have plentiful short setae, raised up, more so in Australian than in African species. 6. Biology: (a) mostly nocturnal, (b) nests are at honey bait, (e) quickly scatter when disturbed by torch light.

Distribution based on Regional Taxon Lists
Australasian Region: Australia.

Biology
The phylogeography of a group of Pacific Island Camponotus species, which included a number of species groups, was broadly examined by Clouse et al. (2015). They found Camponotus humilior is a member of a clade (Clade V) that originated in the Australian wet tropics and has become much more widespread and specieous.

Nomenclature

 *  humilior. Camponotus maculatus var. humilior Forel, 1902h: 497 (s.w.) AUSTRALIA. Wheeler, G.C. & Wheeler, J. 1968: 220 (l.). Subspecies of maculatus: Taylor & Brown, D.R. 1985: 116. Raised to species: McArthur & Leys, 2006: 108.

Worker
Length 5 to 6 mm. Major worker is smaller even then C.oertzeni but it has a shorter head, more widened behind and the sides a little more convex than the type. In addition the hairs on the tibias and scapes are a little more adpressed, without being entirely that, and the thorax and gaster are a yellowish brown much lighter than the head. The minor worker is lighter, of a brownish yellow. otherwise like the novaehollandiae type. McArthur and Leys (2006) - HW 1.0-2.1; HL 1.45-2.3; PW 0.85-1.2; (n = 10). Mesosoma elongate with a distinct but well rounded propodeal angle; yellowish, head slightly darker than mesosoma; tibiae and scapes with distinct setae raised up to 30°, a few scattered long setae overall including under head; frontal carinae widely spaced. Major worker. Head sides posterior half parallel, anterior tapering to front; anterior margin of clypeus, strongly projecting with 90° corners, feebly concave between; node summit blunt; eye centres at or just anterior to line joining posterior tips of frontal carinae. Minor worker. Head sides mostly parallel, occipital carinae distinct; posterior rounded; anterior margin of clypeus, strongly projecting with square corners, wide, straight; ratio propodeal dorsum/declivity about 3.

References based on Global Ant Biodiversity Informatics

 * Clouse R. M., B. D. Blanchard, R. Gibson, W. C. Wheeler, and M. Janda. 2016. Taxonomic updates for some confusing Micronesian species of Camponotus (Hymenoptera: Formicidae: Formicinae). Myrmecological News 23: 139-152.
 * Emery C. 1911. Formicidae. Résultats de l'expédition scientifique néerlandaise à la Nouvelle-Guinée en 1907 et 1909 sous les auspices de Dr. H. A. Lorentz. Nova Guin. 9: 249-259
 * McArthur A. J., and R. Leys. 2006. A morphological and molecular study of some species in the Camponotus maculatus group (Hymenoptera: Formicidae) in Australia and Africa, with a description of a new Australian species. Myrmecologische Nachrichten 8: 99-110.
 * Viehmeyer H. 1912. Ameisen aus Deutsch Neuguinea gesammelt von Dr. O. Schlaginhaufen. Nebst einem Verzeichnisse der papuanischen Arten. Abhandlungen und Berichte des Königlichen Zoologischen und Anthropologische-Ethnographischen Museums zu Dresden 14: 1-26.