Rhytidoponera arborea

This rainforest species is probably arboreal and forages on low vegetation and on the ground.

Identification
In comparison with other pulchella-group species having a dense mat of appressed pubescence on the gastric tergies, arborea is either larger (HW >1.10 in arborea, HW < 1.0 in pulchella and insularis) or differs in pilosity (depilis has little erect pilosity; terrestris is a little more setose than arborea). Rhytidoponera arborea and Rhytidoponera terrestris are rather similar, but the differences between them appear to be consistent. The occipital lobes are a little better developed in arborea (OLI 0.43-0.46 in arborea, 0.40-0.44 in terrestris) and not as far apart (OLD 0.62-0.66 in arborea, 0.66-0.71 in terrestris) (samples of 10 and 13 workers for arborea and terrestris, respectively). The scapes and femora of arborea have fewer standing hairs, as shown by the following ranges of setal counts (data on pulchella are included for comparison):

Finally, arborea and terrestris occur sympatrically (Col d' Amieu; vicinity of Col de Ho), and they are substituted for alternate alleles at three allozyme loci (amylase, esterase, and gluatamate oxaloacetate transaminase).

Distribution
This taxon was described from New Caledonia.

Biology
Rhytidoponera arborea has been collected in rainforest, from 40 to 450 m elevation, where workers were observed foraging on low foliage and on the ground. The present records suggest that this species may favor arboreal nesting sites; one colony was located in a cavity of a living rainforest tree, 10 m above the ground; another was nesting in an epiphytic fern (Asplenium) growing on a large boulder.

Description
Type Material

Holotype worker. New Caledonia: Col d'Amieu Stn, 360 m,  20. ii. 1977, nest in cleft of rainforest tree, 10 m above ground (P.S. Ward acc. No. 2268) (ANIC Type No. 7580).

Paratype workers. A series of nidoparatype workers, same locality, date, and accession number (ANIC, BPBM, MBNH, MCZ, PSW).

Non-paratypic material. Additional material from 6 other localities which is considered to be conspecific is listed below (under Material Examined).

Measurements