Pachycondyla castaneicolor (Dalla Torre 1893)
Synonyms (Valentine & Walker 1991 )
Mesoponera castaneicolor (Dalla Torre), Ponera castaneicolor (Dalla Torre), Ponera castanea Smith
According to Shattuck (1999) there are 277 known species and subspecies of Pachycondyla spread throughout the world. He lists 26 Australian species and subspecies. New Zealand has two endemic species, P. castanea and P. castaneicolor. Evidence points to a derivation of castanea from castaneicolor (R.W. Taylor pers. comm.). Those species of the genus inhabiting the Australian, Melanesian and Indo-Malayan regions appear to be closely related.
Distribution (see map)
On both major islands. On the South Island distribution is restricted to the northern region (Nelson and Marlborough) and to the West Coast as far south, according to collection records, as Haast.
In the genus Pachycondyla, the mandibles are triangular with numerous small teeth along the inner margins; the mandibles touch the front of the clypeus when closed; the single node of the petiole has distinct front, top and rear faces; each tibia of the hind legs has two spurs, one large and comb-like and one small and simple.
Diagnostic features of the worker
Length 5.5–6.4 mm; antennae 12-segmented; eyes with 40–50 ommatidia; mandibles, metanotal groove as for castanea; colour of head, body, legs uniformly yellowish to orange brown.
P. castaneicolor has winged (alate) queens, whereas P. castanea has wingless and worker-like (ergatoid) queens (Wilson & Taylor 1967). Workers are very timid, disappearing rapidly into their nest galleries when disturbed. Colonies are modest in size (probably in the tens rather than hundreds). P. castaneicolor seems to prefer nesting in open habitats (e.g. roadsides, pastures, domestic vegetable gardens), while castanea favours shady native forests. Both species exploit the same nest sites — in soil under stones or in rotting logs.
Highly predatory, they use an effective sting to immobilise prey.
Commonly sampled in pitfall traps, litter and on sweet baits.
Pachycondyla is commonly encountered in gardens (particularly P. castaneicolor), they have an effective sting and have been reported stinging people when the nests are disturbed.
Compiled by Warwick Don & Richard Harris