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Species: Iridomyrmex anceps   (Roger, 1863) 

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Current Valid Name:

Taxonomic History (provided by Barry Bolton, 2023)

Formica anceps Roger, 1863a PDF: 164 (w.) WEST MALAYSIA. Indomalaya. Primary type information: Primary type material: neotype worker (by designation of Heterick & Shattuck, 2011 PDF: 42). Primary type locality: neotype Malaysia: Kuala Lumpur, 9.ii.1967, A-290-1 (D.H. Murphy). Primary type depository: ANIC. Type notes: Original type data: holotype (?) worker [no indication of number of specimens is given]: Malaysia: Malacca (no collector’s name), depository unknown. Heterick & Shattuck, 2011 PDF: 42, say type material “could not be located”, and is “probably destroyed”. AntCat AntWiki HOL

Taxonomic history

Neotype designation: Heterick & Shattuck, 2011 PDF: 42.
Combination in Iridomyrmex: Emery, 1893m PDF: 168.
Status as species: Roger, 1863b PDF: 13; Smith, 1871a PDF: 307; Dalla Torre, 1893 PDF: 168; Forel, 1895f PDF: 469; Emery, 1895m: 475; Forel, 1895f PDF: 469; Emery, 1900: 694; Forel, 1902j PDF: 468; Rothney, 1903: 98; Bingham, 1903 PDF: 298; Forel, 1907d PDF: 27; Forel, 1912a PDF: 71; Forel, 1912o PDF: 62; Stitz, 1912 PDF: 509; Emery, 1913a PDF: 23; Forel, 1913g PDF: 197; Forel, 1913l PDF: 90; Viehmeyer, 1916a PDF: 142; Wheeler, 1919f PDF: 99; Santschi, 1920h PDF: 172; Santschi, 1924c PDF: 112; Karavaiev, 1926d PDF: 433; Wheeler, 1927d PDF: 7; Wheeler, 1928c PDF: 29; Santschi, 1928h PDF: 131; Wheeler, 1929h PDF: 62; Wheeler, 1930k PDF: 72; Stitz, 1932b PDF: 733; Karavaiev, 1935a PDF: 108; Teranishi, 1940: 59; Chapman & Capco, 1951 PDF: 188; Wilson & Taylor, 1967b PDF: 78; Taylor, 1967b PDF: 1094; Taylor & Brown, 1985: 96; Taylor, 1987a PDF: 31, 33; Wu & Wang, 1992c PDF: 1310; Dlussky, 1994a: 55; Shattuck, 1994 PDF: 99; Bolton, 1995b: 217; Wu & Wang, 1995a: 123; Tang et al., 1995: 89; Collingwood et al., 1997 PDF: 509; Mathew & Tiwari, 2000 PDF: 338; Zhou, 2001a PDF: 161; Lin & Wu, 2003: 60; Jaitrong & Nabhitabhata, 2005 PDF: 23; Clouse, 2007b PDF: 203; Don, 2007: 192; Terayama, 2009 PDF: 198; Heterick & Shattuck, 2011 PDF: 40 (redescription); Collingwood et al., 2011 PDF: 415; Pfeiffer et al., 2011 PDF: 33; Guénard & Dunn, 2012 PDF: 25; Sarnat & Economo, 2012 PDF: 33; Sarnat et al., 2013 PDF: 69; Borowiec, 2014 PDF: 83; Ramage, 2014 PDF: 156; Bharti et al., 2016 PDF: 19; Jaitrong et al., 2016 PDF: 22; Dias et al., 2020 10.3897/zookeys.967.54432 PDF: 18; Khachonpisitsak et al., 2020 10.3897/zookeys.998.54902 PDF: 16; Wang et al., 2022 10.20362/am.015006 PDF: 24.
Material of the unavailable name Iridomyrmex anceps papuanus neocaledonica referred here by Taylor, 1987a PDF: 33; Shattuck, 1994 PDF: 99; Bolton, 1995b: 217.


Iridomyrmex anceps is a dull, light to dark brown polymorphic species with large inset eyes high on the head, dense pubescence, relatively long limbs, and distinctive anterior clypeal margin with three convexities. While most Iridomyrmex species are restricted to Australia and New Guinea, I. anceps occurs more broadly. The species is found in the Old World from India, China and Malaysia through the Philippines and Indonesia, across northern Australia and throughout Melanesia, Micronesia and into Polynesia. It is not known whether I. anceps has increased its range with the assistance of human-mediated dispersal, or if its current range was already established prior to contact with humans. The species is present on Tokelau, which is the easternmost Pacific Island with a native ant fauna, but has not been reported from Hawaii. The species is not considered a significant pest across any of its range.

// Distribution


  Geographic regions (According to curated Geolocale/Taxon lists):
    Asia: Bangladesh, Borneo, China, India, Indonesia, Krakatau Islands, Laos, Malaysia, Myanmar, Philippines, Singapore, Sri Lanka, Taiwan, Thailand, Timor-Leste, United Arab Emirates, Vietnam
    Oceania: Australia, Cook Islands, Fiji, French Polynesia, Kiribati, Marshall Islands, Micronesia, New Caledonia, New Zealand, Northern Mariana Islands, Palau, Papua New Guinea, Solomon Islands, Tokelau, Wallis and Futuna
  Biogeographic regions (According to curated Bioregion/Taxon lists):
    Australasia, Indomalaya, Oceania, Palearctic
  Native to (according to species list records):
    Australasia, Indomalaya, Oceania bioregions

Distribution Notes:

Malaysia, India, China, Philippines, Indonesia, Australia, Micronesia, Papua New Guinea, Fiji, Tokelau. United Arab Emirates population may be introduced. 


The confusion surrounding what part, if any, of the range is introduced is driven by the taxonomic uncertainty of the I. anceps group. Heterick & Shattuck (2011)recently synonymized six names with I. anceps, lumping the group across its entire range into a single species. Arguments for treating the taxa involved instead as a group or complex of species were made by Hoffman et al. (2011). It is the opinion of the authors that a more comprehensive study of the entire group across its entire range, possibly with the aid of molecular tools, is required to answer the question.

Iridomyrmex anceps had long been considered to have established an introduced population in New Zealand (e.g. (Faulds, 1970; Lester, 2005)), but the ants were later confirmed to be a species distantly related to I. anceps (Don, 2007). Iridomyrmex anceps is reported from the United Arab Emirates, but the record is not discussed in either Heterick & Shattuck (2011)or Hoffman et al. (2011). Wilson & Taylor (1967)claimed that the specimen of I. anceps collected at the Nadi airport in Fiji was evidence of the species’ eastward expansion into the Pacific. That claim is obviated, or at least pushed back a half century, by the recent synonymy of I. anceps ignobilis (Mann) which Mann described from Fiji in 1921. The distribution of I. anceps in Fiji is limited to the mostly disturbed habitat on the western (leeward) side of Fiji’s largest island, Viti Levu, suggesting perhaps that it is a relatively recent arrival that has not dispersed to the full extent of its capacity (Sarnat & Economo, In Press). The species was found by Ward (2007)to be aggressive at baits, but such behavior was not observed by the less rigorous observations reported in Sarnat & Economo (In Press). Given the success of I. anceps on Pacific islands, it is somewhat surprising that it has not yet been found in Hawaii.


Diagnosis among workers of introduced and commonly intercepted ants in the United States. Worker caste weakly polymorphic, but lack distinct major caste. Antenna 12-segmented. Antennal scape length less than 1.5x head length. Eyes medium to large (greater than 5 facets); placed at or above midline of face. Eyes do not break outline of head. Antennal sockets and posterior clypeal margin separated by a distance less than the minimum width of antennal scape. Anterior clypeal margin with one median and two lateral rounded projections. Mandible with distinct basal angle. Dorsum of mesosoma lacking a deep and broad concavity, with erect hairs that are thin and flexuous. Promesonotum separated from propodeum by metanotal groove. Propodeum and petiolar node both lacking a pair of short teeth. Propodeum lacking posteriorly projecting protrusion; dorsal surface not distinctly shorter than posterior face. Waist 1-segmented. Petiole upright and not appearing flattened. Gaster armed with ventral slit. Distinct constriction not visible between abdominal segments 3+4. Color uniformly light to dark brown.

Among introduced and commonly intercepted ants in the United States, I. anceps is most likely confused with dolichoderines with upright petiolar nodes and inset eyes that do not break the outline of the head, namely Dolichoderus, Linepithema and Ochetellus species. The low propodeal profile and convex propodeal declivity of I. anceps separates it from Dolichoderus and Ochetellus species. Iridomyrmex anceps is separated from Linepithema species by (1) eyes that are situated at or above the midline of the head; (2) mandibles with distinct basal angles; and (3) anterior clypeal border with one median and two lateral convexities. 


Collingwood, C.A., Tigar, B.J. & Agosti, D. (1997) Introduced ants in the United Arab Emirates. J. Arid Environ., 37, 505-512.

Don, W. (2007) Ants of New Zealand. Otago University Press, Dunedin,pp.

Faulds, W. (1970) A second species of Iridomyrmex Mayr established in New Zealand. N. Z. Entomol., 4(4), 18-19.

Heterick, B.E. & Shattuck, S. (2011) Revision of the ant genus Iridomyrmex (Hymenoptera: Formicidae). Zootaxa, 2845, 1-174.

Hoffmann, B.D., Andersen, A.N. & Zhang, X. (2011) Taxonomic confusion of two tramp ant species: Iridomyrmex anceps and Ochetellus glaber are really species complexes. Curr. Zool., 57, 662-667.

Lester, P.J. (2005) Determinants for the successful establishment of exotic ants in New Zealand. Diversity Distrib., 11, 279-288.

McGlynn, T.P. (1999) The worldwide transfer of ants: geographical distribution and ecological invasions. J. Biogeogr., 26, 535-548.

Sarnat, E.M. & Economo, E.P. (In Press) Ants of Fiji. Univ. Calif. Publ. Entomol.,

Ward, D.F. (2007) The distribution and ecology of invasive ant species in the Pacific Region. PhD thesis, in Biological Sciences, The University of Auckland, xiii + 173 p.

Wilson, E.O. & Taylor, R.W. (1967) The ants of Polynesia (Hymenoptera: Formicidae). Pac. Insects Monogr., 14, 1-109.

Taxonomic Treatment (provided by Plazi)

Specimen Habitat Summary

Found most commonly in these habitats: 2 times found in port of entry/city, 12 times found in Rainforest, 10 times found in Savanna, 4 times found in Pandanus & Casaurina forest, 1 times found in Botanical garden, 30am on a sunny, sunny day (already!) times found in Didn't see Anoplolepis; PB baiting along trail; Iridomyrmex collected in Savannah area ~8, 4 times found in primary forest, 1 times found in veg seems especially short, savannah, no pandanus immediately nearby; monomorium? nest in dead branch of living tree. Camponotus nest in dead stick on ground at base of same tree; 1 or 2 Tapinoma ne, 1 times found in peak of limestone pinnacle, scrubby veg., 3 times found in Dry sclerophyll, ...

Found most commonly in these microhabitats: 2 times recruiting to bait, 5 times under rock, 1 times nesting in sand, 1 times along trail; Iridomyrmex collected in Savannah area, 1 times veg seems especially short, savannah, no pandanus immediately nearby; monomorium? nest in dead branch of living tree. Camponotus nest in dead stick on ground at base of same tree; 1 or 2 Tapinoma ne, 1 times nest in rocky soil, 4 times Malaise trap, 1 times from nest under cement in road, 3 times under stone, 1 times strays ex clay bank Garden, 3 times sieved litter, ...

Collected most commonly using these methods: 5 times hand collected|aspirator, 4 times H, 3 times water traps, 9 times flight intercept trap, 7 times traps, 7 times Pitfall trap, 2 times Hand collection, 6 times Pitfall, 2 times hand collected|aspirator>bait trap|peanut butter, 3 times light trap, 5 times M, ...

Elevations: collected from 5 - 1900 meters, 453 meters average

Collect Date Range: collected between 1865-12-31 00:00:00.0 and 2014-08-02 00:00:00.0

Type specimens: Not Provided: casent0171061, casent0177237, casent0177297, casent0177298, casent0177300, casent0177301, casent0177304, casent0177307, casent0177308, casent0177309, casent0177312, casent0177316, casent0177318, casent0177319, casent0177322, casent0177323, casent0177325, casent0177328, casent0177329, casent0177332, casent0177333, casent0177336, casent0177339, casent0177341, casent0177342, casent0177343, casent0177344, casent0177345, casent0177568, casent0186802, casent0186851, casent0716504, casent0716505, casent0716506, casent0735680, casent0735681, casent0735682; syntype of Iridomyrmex anceps sikkimensis: casent0909500; syntype of Iridomyrmex excisus: casent0915581; syntype of Iridomyrmex gracilis papuanus: casent0905045; syntype of Iridomyrmex anceps watsonii: casent0909501; syntype of Iridomyrmex bicknelli formosae: casent0909507; syntype of Iridomyrmex rufoniger metallescens: casent0905055; type of Formica anceps: focol2796, focol2797; type of Iridomyrmex bicknelli formosae: focol0171, focol0172, focol0176; Type of unavailable quadrinomial: Iridomyrmex anceps papuanus neocaledonica: casent0905047

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