Colobopsis aruensis

Klimes and McArthur (2014), New Guinea rainforest Camponotus canopy ant study - Camponotus aruensis was one of the common Camponotus species in secondary forest (23 nests per 0.32 ha), but was relatively uncommon in primary forest (three nests per 0.32 ha). It was not specialized to particular host trees as it occupied in total 24 trees of 12 species in eight families. The stratification of nests varied between five (nests in liana stems) to 21 m above ground (in dry twigs), however, most of the nests were found in the canopy. The nests were of relatively small size usually not exceeding 500 workers. In contrast to most of the Camponotus species in this study C. aruensis nested exclusively in dead and dry hollow branches, twigs and lianas. This may explain why it was more common in secondary forest, where such nesting habitats were more common. Camponotus aruensis was not observed to be tending scale insects (Coccidae) directly in their nests. However, workers were occasionally observed foraging with ants Technomyrmex albipes to colonies of scale insects that were sucking on twigs and leaf stems high in the canopy.

Identification
Klimes and McArthur (2014) - The colour of workers is black with contrastingly light brown appendages and this colour pattern is consistent within colonies and is the same for the type specimen from Aru island. In side view, the mesosoma dorsum of the minor worker of C. aruensis is similar to that of the related species Colobopsis conica but the latter has a pointed rearward projection on its node whereas in C. aruensis node is rounded and taller. In front view, the head in workers of C. conica is nearly circular whereas the head sides are only weakly convex in C. aruensis.

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

Castes

 * Minor Worker

Nomenclature

 *  aruensis. Camponotus (Colobopsis) aruensis Karavaiev, 1933a: 317, fig. 5 (w.) INDONESIA (Aru I.). Combiniation in Colobopsis: Ward, et al., 2016: 350.

Klimes and McArthur (2014) - Karavaiev described a “badly damaged ant” from Dobo-Wammar Island in the Aru group of Islands of Indonesia (between Australia and New Guinea) as the type for Camponotus aruensis (Karavaiev 1933). He wrote that it had been caught on a low plant and described its head, scape, eye, mandibles and in particular its distinguishing character viz. “pointed propodeal angle. The holotype was examined by AM in the Schmalhausen Institute of Zoology of the Ukrainian National Academy of Science, Kiev (Ukraine) and is photo-documented in McArthur (2012). Karavaiev assigned the species to subgenus Colobopsis and to the conica species group following the definition of Emery (1925), because of its cone-shaped propodeum. He described a minor worker and provided clear drawings of head, node and mesosoma (Karavaiev 1933). However, he did not specify its small size, its sparse pilosity or its integument. We believe that descriptions of other castes have never been published.

Worker
Klimes and McArthur (2014) - Major Structures: in side view, neck attached to head lower down than with most Camponotus, and in that respect back of head resembling Camponotus saundersi. Pronotum strongly convex, mesonotum weakly convex, metanotal groove deep, with protruding spiracles, propodeum flat on top and meet thick and tall, with parallel sides, when viewed from behind summit nearly flat. Front femora almost double the thickness of mid and hind femora. Integument glossy, finely reticulate. Head in front view: sides nearly parallel and very weakly convex, vertex strongly convex. Eyes large, touching lateral cephalic outline in upper third of head. Frontal carinae wide, with distance between them almost two thirds of head width. The anterior part of head including clypeus and mandibles quite flat, separated from the posterior part of head by a distinct angle of about 150°. Head integument glossy, finely punctate on frons. Clypeus and the surrounding frontal parts of head are deeply sculptured, on clypeus two distinct longitudinal carinae, anterior margin of clypeus narrow (one fourth of head width) and mostly straight, mandibles with six or seven teeth.

Pilosity: erect setae extremely sparse, mostly confined to mandibles and funiculus, short indistinct adpressed setae plentiful.

Colour: head and mesosoma mostly black, except for light brown frontal third of head, and coxae. Scapes, tibiae and tarsi lighter yellow.

Minor (in support of Karavaiev's description): Structures: in side view, neck attached to head lower down as in major worker, pronotum and mesonotum convex, metanotal groove deep with protruding spiracles, propodeum strongly convex on top, forming a distinct blunt tooth that meets with the concave declivity at protruding 80° angle. Mesosoma with distinct reticulation, glossy. Node tall, sides parallel, wide when viewed from behind, summit nearly flat; gaster with a few short setae on dorsum. Front femora double the thickness of mid and hind femora. Head in front view: sides nearly straight, weakly tapering to the front, vertex weakly convex. Eyes, frontal carinae and integument similar to major. Clypeus rounded, transversely without sculpture and glossy, its anterior margin wide (three fourth of head width), weakly convex, mandibles appear to have six or seven teeth.

Pilosity: sparse, with a few short erect setae at front of head and gaster, a few adpressed on gaster.

Colour: mostly black, with contrastingly light yellow appendages with exception of femora which are brownish.

Queen
Klimes and McArthur (2014) - CI = 88, EL = 0.42, FCD = 0.60, HL = 1.12, HW = 0.99, ML = 1.93, PW = 1.12, SI = 80, SL = 0.79.

Structures: in side view, mesosoma dorsum mostly flat, pronotum convex, propodeal angle rounded, declivity mostly straight, node small and thick, convex summit. In front view, head similar to major worker, with straight and parallel sides, vertex convex, front of head and clypeus with deep parallel longitudinal grooves. Eyes only slightly larger than in major workers.

Pilosity: sparse.

Colour: dark brown with whitish-yellow femora and suture of gaster; otherwise similar to major worker.

Male
Klimes and McArthur (2014) - CI = 81, EL = 0.32, FCD = 0.22, HL = 0.62, HW = 0.50, ML = 1.3, PW = 0.75, SI = 104, SL = 0.52.

Structures: in side view, mesosoma dorsum mostly weakly convex, propodeal angle rounded, declivity mostly straight, node similar to gyne. In front view, head sides straight and strongly tapering to the front, vertex semi-circular, eye length about half of head length.

Pilosity: sparse.

Colour: yellowish-brown.

Type Material
Klimes and McArthur (2014) - Holotype (minor worker, damaged, pinned, SIZK): Indonesia, “Aru Islands, Dobo Wammar Is.”.