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Monomorium sydneyense Forel 1902

Compiled by Richard Harris and Jo Berry
Biostatus: Introduced


Family: Formicidae
Subfamily: Formicinae
Tribe: Solenopsidini
Genus: Monomorium
Species: sydneyense

Common name 

None reported

Synonyms (Heterick 2001)

Monomorium ( Mitara) sydneyense subsp. nigella Emery , Monomorium ( Lampromyrmex ) fraterculus var. barretti Santschi


Monomorium is a largegenus 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. M. sydneyense is w idespread butnot particularly common in Australia (A. Andersen pers. comm. 2003).


Specimens first identified from Mt Maunganui wharf in March 2003 and several other locations at Sulphur Point and Mount Maunganui Wharf during 2003 (T. Ashcroft pers comm.). Review of earlier Argentine ant surveillance samples revealed specimens from one location in March 2001 (RJH pers. comm.). In 2004 populations were also found around the port of Napier, the site of a fireant incursion (T. Ashcroft pers. comm.).

General Description


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

Monomorphic. Length (excluding gaster) 0.8-1.33mm. Antennae 11-segmented, including a 3-segmented club. Eye elliptical, moderate to large in size. Mandibles each with 4 teeth. Paired longitudinal carinae on clypeus distinct, may or may not be produced as teeth or denticles; clypeal portion between carinae concave or more or less straight. Metanotal groove deep. Propodeum without spines, dorsal surface sloping, posterior surface curved or straight. Propodeum surface sculptured, distinguishing this species from M. antipodum . Two nodes (petiole and postpetiole) present, petiole higher than postpetiole, postpetiole more broadly rounded than petiole. Erect and suberect setae only rarely present on head and alitrunk ( Heterick 2001 ). Body colour variable in colour - yellow to chocolate brown; many individuals bicoloured with gaster, appendages and often head brown or fulvous and alitrunk lighter.


Found in "a wide range of habitats" (Heterick 2001). Occurs in urban areas in Australia, and is quite common in sandy suburban backyards in Perth, even when Pheidole megacephala is present (Heterick 2001). In Tauranga at Sulphur Point, where the majority of the nests were located, the site is a sandy substrate with the bank overgrown with weeds and the northern face of the bank is exposed to the sun throughout the day (T. Ashcroft pers. comm.). Nests appear to be large in New Zealand compared to Australia, possibly reflecting an ideal site (T. Ashcroft pers. comm.), or lack of competition from other ants. The ants forage 24 hours a day and close to the nest (mostly within 3 m) (P. Lester pers. comm.). They show inter-colony aggression and do not appear to exclude other ant species from the area of establishment but do appear to dominate baits within the area (P. Lester pers. comm.).

Dispersal most likely by flight (A. Andersen pers. comm. 2003).

Pest Status

Occur in urban areas in Australia (Heterick 2001) , although does not invade houses. May be a minor garden nuisance.