Prolasius advenus (Fr. Smith 1862)
Small brown bush ant (Ferro et al. 1977)
Synonyms (Valentine &Walker 1991 )
Formica zealandica Smith, Formica advena Smith, Prenolepis advena var. zealandica Wheeler, Prenolepis advena (Smith), Lasius (Prolasius) advena (Smith), Lasius advena (Smith), Meloporus advena (Smith), Lasius zealandica (Smith), Meloporus (Prolasius) advena (Smith), Colobopsis zealandica (Smith), Prolasius zealandica (Smith).
Prolasius is very much an Australian genus. Of the 19 known species, 18 are found in Australia (Shattuck 1999). The one New Zealand species is edemic to this country but with an Australian affinity.
Distribution (see map)
P. advenus is widely distributed on all three main islands, Three Kings Is (Taylor 1962; Don 1994) and offshore islands.
One of only two genera of Formicines in New Zealand, which are distinguished by the absence of a sting, and the tip of the gaster bearing a small poison-ejecting nozzle (acidopore) surrounded by a brush of short hairs. The other genus, Paratrechina, has pairs of large, stout, dark hairs on the upper surface which are absent in Prolasius.
Diagnostic features of the worker
Length 2.9-3.5 mm; antennae 12-segmented mandibles with 6 teeth; petiolar node wedge-shaped and notched dorsally (notch visible from in front). Colour usually brown, apart from the gaster which is darker than the head and mesosoma.
This species inhabits native forests, nesting in soil under stones, or in or under rotting logs. It is found occasionally nesting in the open but still close to the forest edge.
Colonies can be populous (hundreds of workers), multi-queened and complex. P. advenus is a generalist, foraging and scavenging for small arthropods and tending mealy bugs. Food exchange (trophallaxis) takes place between workers and larvae. The developing pupae are enclosed in pale cream coloured silken cocoons.
Several associations of this ant with beetles are known. Beetle species include the following: a staphylinid (Holotrochus sp.), a small endemic stag beetle (Ceratognathus passaliformis), and a pselaphid beetle (Ecomorypora granulata). There is also an interesting association with the caterpillars of the puriri moth (Aenetus virescens) that live in putaputaweta trees (Carpodetus serrata). The worker ants feed on sap exposed by the wound created in the callus tissue of the tree by the moth larvae.
It is commonly sampled in litter and moss extractions and pitfall traps.
Impacts not known, but considered unlikely to be a pest.
Compiled by Warwick Don & Richard Harris