Colobopsis conithorax

B.P.M. Hyland collected specimens nesting in a hollow twig of Endospermum at Bamaga, Queensland.

Identification
A member of the Camponotus macrocephalus species-group. This group has the following characters:


 * Fore femurs swollen, much greater in diameter than middle and hind femurs, generally more swollen than in most other Camponotus species.
 * Spines or bristles on the lower surfaces of the tibiae lacking, or at most, only one or two (most Camponotus species possess two rows of 5 to 10 spines).
 * Major workers and queens with the anterior of the head is truncated and flattened (phragmotic).
 * Major and minor workers present, but not intermediate-sized workers (worker caste dimorphic).

Within this group, this species can be diangosed as follows:

Propodeum appears conical when viewed from side, upper and posterior surfaces straight and separated by an angle just greater than 90°. Scapes and tibiae with plentiful short fine setae, raised to an angle of about 10°. Very few erect setae on the outer surface of the head and none on the under side.

Distribution based on Regional Taxon Lists
Australasian Region: Australia. Indo-Australian Region: New Guinea, Vanuatu.

Nomenclature

 *  conithorax. Camponotus (Colobopsis) conithorax Emery, 1914f: 430, pl. 13, fig. 18 (w.q.m.) VANUATU. Combination in C. (Myrmotemnus): Emery, 1920b: 258; in C. (Colobopsis): Emery, 1925b: 148. Combination in Colobopsis: Ward, et al., 2016: 350. See also: McArthur & Shattuck, 2001: 30.

Major worker
In lateral view. Pronotum, anterior mesonotum, limbs and gaster brown, posterior mesonotum, propodeum and node darker brown, nearly black. Head: Dark brown, lighter in front; side glossy, smoothly reticulate with very sparse flatlying short setae; scape dark brown like posterior head; funiculus lighter like anterior head; vertex with one or two erect setae; underside of head without erect setae, with few very short adpressed setae. Pronotum: Glossy, flatly convex, dorsum with one or two long setae, without pubescence. Mesonotum: Glossy, evenly convex without setae or pubescence. Metanotum: Separated from mesonotum and propodeum by deep transverse cuts raised up in centre; spiracles placed well below dorsum, slightly protruding upward. Propodeum: Posterior dorsum inclined upward, conical, glossy, with few short adpressed setae; angle approximately 90°, sharply rounded; declivity mostly straight; ratio dorsum/declivity approximately 1; spiracle protruding to rear, surrounded by glossy integument with a few short indistinct Flat-lying setae. Node: Glossy with sparse flat-lying and sparse erect, short setae; anterior face convex above; summit blunt; posterior face straight. Gaster: Dark brown, lighter posteriorly; glossy. Fore femur: Swollen. Mid tibia: Plentiful short, decumbent setae, without bristles inside. In dorsal view. Head: Sides straight, parallel; vertex straight; scape with sparse, short Flat-lying setae; frontal carinae wide, diverging strongly then converging slightly at posterior; frontal area diamond shaped with an anterior pit; max HW at eye centre. Truncation: Near posterior clypeus. Clypeus: Sides mostly parallel, long, diverging anteriorly, with few feeble striations and punctations, without furrows, glossy, with few very sparse, flat-lying setae, anterior margin projecting, mostly straight with weak median concavity, with few long setae; without carina. In front or rear view. Node: Narrow, summit straight with few short setae.

Minor worker
In lateral view. Pronotum, anterior mesonotum and gaster brown; posterior mesonotum, propodeum and node darker brown, limbs a little lighter coloured than mesosoma. Head: Dark brown, grading to yellowish brown anteriorly; side with sparse flat-lying short setae; glossy, smoothly reticulate; scape dark brown, like posterior head; funiculus lighter, like anterior head, vertex with sparse, short, flat-lying setae; underside of head without erect setae, with few very short, adpressed setae. Pronotum: Anterior third convex, otherwise straight without setae or pubescence. Mesonotum: Evenly flatly convex, dorsum without setae or pubescence. Metanotum: Separated from mesonotum and propodeum by deep transverse cuts, raised in the centre; spiracles placed well below dorsum, slightly protruding up. Propodeum: Dark brown with few short adpressed setae; dorsum slightly convex, slightly inclined upward; angle blunt 90'; declivity very straight; ratio dorsum/ declivity near 1; spiracle protruding to rear surrounded by glossy integument with few short, sparse setae. Node: Glossy with few very short, erect setae; petiole with ventral protuberance; lower half of anterior face of node straight, otherwise convex; summit blunt; posterior face mostly straight. Gaster: Glossy. Fore femur: Swollen. Mid tibia: With short decumbent setae, lacking bristles inside. In dorsal view. Head: Sides flatly convex, tapering to front; vertex convex; scape with sparse, short, flat-lying setae; frontal carinae wide, nearly parallel; frontal area diamond shaped, indistinct; max HW at eye centre. Clypeus: Glossy with few sparse flat-lying and erect setae, without canna; anterior margin wide, mostly straight, projecting but not beyond cheeks. In front or rear view. Node: Narrow, summit rounded with few erect long setae.

Measurements
HW 1.5-2.1 mm, HL 1.6-2.3 mm, PW 1.1-1.3 mm, FIT 1.2-1.6 mm, EL 0.4-0.5 mm,TL 1.6-1.9 mm.

References based on Global Ant Biodiversity Informatics

 * CSIRO Collection
 * Kami K.S., and S. E. Miller. 1998. Samoan insects and related arthropods: checklist and bibliography. Bishop Museum Technical Report 13, pp 121.
 * Kami KS & Miller SE. 1998. Samoan insects and related arthropods: checklist and bibliography. Bishop Museum Technical Report No. 13.
 * Room P. M. 1975. Diversity and organization of the ground foraging ant faunas of forest, grassland and tree crops in Papua Nez Guinea. Aust. J. Zool. 23: 71-89.
 * Wetterer, James K. and Vargo, Donald Vargo L. 2003. Ants (Hymenoptera: Formicidae) of Samoa. Pacific Science. 57(4):409-419.
 * Wheeler W.M. 1935. Check list of the ants of Oceania. Occasional Papers of the Bernice Pauahi Bishop Museum 11(11):1-56.