Solenopsis papuana
Solenopsis papuana is a minute pale yellow species with 10-segmented antennae, two-segmented antennal clubs, no antennal scrobes, minute eyes, no propodeal spines, unsculptured heads and bodies, abundant thin and erect pilosity, and a monomorphic worker caste. Like all myrmicines, S. papuana has a two-segmented waist and a gaster armed with a stinger. Solenopsis papuana is a small species, but nests will recruit in vigorous force to baits and food resources. They can defend the bait from competing ants with use of their stings. The species occurs both in urban landscapes and natural forests. For a more complete review of the biology, impacts and management of S. papuana, users are referred to the IUCN/SSC Invasive Species Specialist Group (ISSG) web page.
Diagnosis of worker among Antkey species. Worker caste monomorphic. Total length < 2 mm. Head ovoid. Antenna 10-segmented. Antennal club 2-segmented. Antennal scapes not conspicuously short; easily extended beyond eye level. Antennal insertions at least partly covered by frontal lobes; not surrounded by a raised sharp-edged ridge. Antennal scrobe lacking. Posterolateral corners of head unarmed, without spines. Eyes small (less than 5 facets). Frontal lobes do not obscure face outline between mandible and eye. Mandibles triangular. Pronotal spines absent. Propodeum lacking spines or teeth. Petiole with peduncle; subpetiolar process not developed as a flange or lobe. Color shiny reddish brown.
Solenopsis papuana is easily separated from all other introduced and commonly intercepted Solenopsis species by the monomorphic worker caste, the smaller size (TL < 2.0 mm), and by the small eye (> 5 facets).