Camponotus triangulatus

We discovered only one nest of this species in a primary forest plot. It occupied a dead branch in a Macaranga punctata K. Sshumc tree of small size (dbh = 9 cm, nest 7 m above ground) and it shared the tree with another common arboricolous ant species at the site, Anonychomyrma cf. scrutator Smith, 1859. It did not tend scale insects and it was not observed to be nesting in live branches. Workers were also found to be foraging actively on the nearby trees and vegetation. This may suggest opportunistic feeding and nesting behaviour, but more ecological data are needed due to the rarity of this species in our studied forest. (Klimes & McArthur 2014)

Identification
Klimes & McArthur (2014) - length is greater in minor than major workers, the latter having considerably shortened scapes compared with their head width. Species is dimorphic. In minor worker, the anterior margin of clypeus projects strongly and resembles two sides of an equilateral triangle, whereas in major worker it is concave. These characters separate it from all other Camponotus species with phragmosis.

Distribution based on Regional Taxon Lists
Indo-Australian Region: New Guinea.

Castes
Known only from the worker caste.


 * Minor Worker

Nomenclature

 *  triangulatus. Camponotus triangulatus Klimes & McArthur, 2014: 150, fig. 9 (w.) NEW GUINEA.

Worker
Major Structures: in side view, front of head weakly convex with 135° angle separating the forehead from the clypeus which is straight. Pronotum strongly convex, mesonotum weakly convex and propodeum dorsum weakly concave, metanotum shallow, the propodeal angle well rounded, declivity straight, ratio dorsum / declivity about 1.2. Node thick, front convex, back mostly straight, summit blunt. Fore femora about 1.5 thicker than others. Integument: glossy, very finely striate. Head in front view: sides straight and near parallel, vertex straight; most of clypeus, anterior head and closed mandibles forming a circular flat surface. Anterior margin of clypeus projecting a little, concave in the centre, clypeus with four to six distinct parallel ridges posteriorly, similar ridges also on front of head at sides of clypeus. Mandibles with six teeth. Frontal carinae distance approximately half of head width.

Pilosity: erect setae very sparse, none on mesosoma or gula, a few sparse short decumbent setae, no erect setae on scapes.

Colour: mostly black-brown; mesonotal suture, coxae and suture of gaster whitish-yellow.

Minor Structures: in side view, front of head weakly convex overall, clypeus depressed. Pronotum slightly convex, mesonotum convex and propodeum dorsum raised up and weakly concave, metanotum indistinct, propodeal angle narrowly rounded, declivity straight, ratio dorsum / declivity about 1. Node thick, front convex, back mostly straight, summit blunt. Fore femora about 1.5 times thicker than others. Integument: similar to major workers, but less glossy. Head in front view: sides straight, weakly tapering to the front, vertex convex; clypeus anterior margin projecting strongly like two sides of an equilateral triangle, without a carina. Mandibles with four teeth. Frontal carinae separated by half of head width.

Pilosity: erect setae very sparse, none on mesosoma or gula, a few more short decumbent setae than in major workers, no erect setae on scapes.

Colour: mostly black. Mesonotal suture, mandibles and coxae whitish-brown. Tarsi and basal area of scapes light-brown.

Type Material
Holotype (minor worker, ): “Papua New Guinea: Madang Province, Wanang (05°14' S, 145°11' E), 21.VIII.2007, HP0213, leg. P. Klimes}. Paratypes: From the same nest series, labelled as above: 2 minor workers, 2 major workers (SAMA); 1 minor worker and 1 major worker ; 2 minor workers and 2 major workers.

Etymology
Named after the triangular shape of clypeus in minor workers.

References based on Global Ant Biodiversity Informatics

 * Klimes P., P. Fibich, C. Idigel, and M. Rimandai. 2015. Disentangling the diversity of arboreal ant communities in tropical forest trees. PLoS ONE 10(2): e0117853. doi:10.1371/journal.pone.0117853
 * Klimes P., and A. McArthur. 2014. Diversity and ecology of arboricolous ant communities of Camponotus (Hymenoptera: Formicidae) in a New Guinea rainforest with descriptions of four new species. Myrmecological News 20: 141-158.