Monomorium antarcticum (Fr. Smith 1858)
Southern ant (Ferro et al. 1977)
Synonyms (WWW5; Valentine & Walker 1991 )
Atta antarctica Smith, Monomorium fulvum Mayr, Tetramorium nitidum Smith, Monomorium suteri Forel, Monomorium integrum Forel, Monomorium succineum Stitz, Aphenogaster antartica (Smith) , Monomorium Notomyrmex) rapaense Wheeler, Formica antarctica (Smith), Monomorium nitidum (Smith), Monomorium (Notomyrmex) antarcticum (Smith), Monomorium (Notomyrmex) integrum (Forel), Monomorium (Notomyrmex) nitidum (Smith), Monomorium (Notomyrmex) succineum Stitz, Chelaner antarcticus (Smith), Chelaner antarctica (While)
Monomorium is a large genus with well over 300 species. Bolton (1987) observes that the main centres of speciation include Africa and Australia. Heterick (2001) recognises 59 endemic species in Australia. New Zealand has two endemic species, M. antarcticum and M. smithii, and a probable endemic in M. antipodum, all with a likely Australian affinity.
Distribution (see map)
M. antarcticum is by far New Zealand’s most ubiquitous ant species, being found throughout the North and South Islands, on Stewart I., Three Kings Is, Chatham Is and offshore islands.
In the genus Monomorium, antennae of the workers are 10 to 12-segmented (most often 12), usually with a conspicuous, 3-segmented club. The front margin of the clypeus has a single central elongate hair. Metanotal groove present, either deeply or feebly impressed. Petiole and, generally, the postpetiole have distinct rounded nodes.
Diagnostic features of the worker
Polymorphic, length 3 - 5 mm; antennae 12-segmented; mandibles usually 5-toothed; metanotal groove distinct or feebly impressed; smooth and shiny without sharp spines on the propodeum (cf. Huberia species); some antarcticum populations have blunt spines on the propodeum; body colour variable (but uniform within a colony) — orange, yellowish brown, dark brown, black; in all colour forms, apart from black, the antennae and legs are a different shade from the body (c.f. M. smithii).
M. antarcticum is highly variable in size and colour, and occurs in a wide variety of habitats, at low and high altitudes (see below). This variety may indicate either a highly variable species, or a complex of several species. Comparative analyses of poison gland alkaloids extracted from workers collected from colonies throughout the country lend weight to the second alternative (Jones et al. 1988; Don & Jones 1993).
This species is a generalist, preying on small insects, scavenging and “milking” homopterans. Small seeds may be harvested, suggesting a possible impact on the establishment of pasture grasses. Workers forage haphazardly rather than following specific routes, which is in line with the apparent absence of trail pheromones (Blum 1966). Nests can be small or highly populous with thousands of workers; construction can be complex with galleries at different levels, particularly in soil under stones. Nests also occur in and under rotting logs. Habitats exploited include native forests and grasslands, pastures and household gardens.
Homopterans associated with this species include the pseudococcids (mealybugs), Dactylopius poae Maskell [now called Balanococcus poae (Maskell)] and Ripersia formicicola Maskell [now called Dysmicoccus formicicola (Maskell)] (W.W.Smith 1896).
Commonly sampled in pitfall traps and litter and moss extractions and workers are attracted to a wide variety of baits.
Common in urban environments. Can be a minor nuisance due to their attraction to a variety of foods, but do not forage indoors. They have a strong bite (RJH pers. experience).
Compiled by Warwick Don & Richard Harris