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Temporal range: 37.2–0 Ma Middle Eocene – Recent
Pseudolasius australis
Scientific classification
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Hymenoptera
Family: Formicidae
Subfamily: Formicinae
Tribe: Lasiini
Genus: Pseudolasius
Emery, 1887
Type species
Formica familiaris, now Pseudolasius familiaris
66 species
1 fossil species
(Species Checklist, Species by Country)

Pseudolasius australis casent0106005 profile 1.jpg

Pseudolasius australis

Pseudolasius australis casent0106005 dorsal 1.jpg

Specimen Label

Evolutionary Relationships

  (2 genera)


  (13 species)

  (141 species)

  (30 species)

  (6 species)

  (42 species)

  (19 species)

  (149 species)

  (66 species)

  (8 species)

  (6 species)

  (9 genera)

  (8 genera)

Gesomyrmex, Oecophylla

  (9 genera)

Gigantiops, Myrmoteras, Santschiella

  (8 genera)

Based on Ward et al. (2016) and Matos-Maravi et al. (2018).

Pseudolasius are perhaps best known for possessing a polymorphic worker caste, with most species having completely dimorphic majors (soldiers) and minors (LaPolla, 2004).


Mandible with 4 to 7 teeth; maxillary palps 2-to 5-segmented; labial palps 2- to 4-segmented; mandalus small and inconspicuous. Setae on dorsum of head randomly placed; with erect setae on scapes, legs and dorsum of mesosoma, including propodeum; body often covered in dense pubescence. Eyes often poorly developed, typically placed below midlength. Workers strongly polymorphic, with a major caste present; posterior margin of head in majors typically emarginate. Propodeum with a low- to high-domed dorsal face; overall mesosoma shape compact. (LaPolla et al. 2010)

Keys including this Genus


Keys to Species in this Genus


This genus is restricted to southern Asia, from India to China, stretching southwards to northern Australia. It appears to be restricted to tropical localities.

Distribution and Richness based on AntMaps


Fossils are known from: Baltic amber (Bartonian, Middle to Late Eocene), Bitterfeld amber (Bartonian, Middle to Late Eocene) and Rovno amber (Priabonian, Late Eocene).


All species are apparently hypogeic. They convergently resemble Acropyga and especially subterraneous Lasius in colour and morphological characters, but are, however, polymorphic. The sociobiology of Pseudolasius is virtually unknown.

In Malaysian lowland rainforests, three Pseudolasius species are involved in mutualistic relationships with a total of eight scale insect species in six genera feeding at the roots of plants (Malsch et al. 2001). The ants feed on honeydew excreted by the mealybug partners, and these (both adults and immature instars) are kept in chambers with and without ant brood. All three species carry their mealybugs (1) when disturbed, (2) during nest movements, and (3) to feeding sites. Ants build flat soil pavilions around their mealybug feeding sites and tend their trophobiosis partners. It is assumed that Pseudolasius queens do not co-disperse with their associated mealybugs during mating flight.

These Pseudolasius spp. are highly polydomous, which results in an extremely decentralized colony structure. Numerous small nest chambers were either widely distributed in the top soil (Pseudolasius sp.2 and sp.3) or predominantly in small decaying twigs (Pseudolasius sp.1). Pseudolasius sp. 1 and Pseudolasius sp. 2 are polygynous.


Head of worker Side of worker

Major worker of Pseudolasius from Queensland.

Head of worker Side of worker

Minor worker of Pseudolasius from Queensland.


Worker Morphology

  • Antennal segment count: 11; 12
  • Antennal club: absent-gradual, weak
  • Palp formula: 5,5; 5,3; 4,3 3,3; 2,3; 2,2
  • Total dental count: 4-7
  • Spur formula: 1 simple1 simple; 0, 0
  • Eyes: present
  • Scrobes: absent
  • Caste: mostly dimorphic or polymorphic
  • Sting: absent

Palp formula 5,3 in an undescribed species from Vietnam.


Species Uncertain

  • Pseudolasius sp.1: n = 8 (Malaysia) (Imai et al., 1983).
  • Pseudolasius sp.2: n = 15, 2n = 30 (Malaysia) (Imai et al., 1983) (B Chromosome polymorphism).
  • Pseudolasius sp.2: n = 17, 2n = 30 (Malaysia) (Imai et al., 1983) (B Chromosome polymorphism).
  • Pseudolasius sp.2: n = 19, 2n = 30 (Malaysia) (Imai et al., 1983) (B Chromosome polymorphism).
  • Pseudolasius: n = 14 (Taiwan) (Hung et al., 1972) (near Pseudolasius emeryi).
  • Pseudolasius: 2n = 30 (Indonesia) (Imai et al., 1985).
  • Pseudolasius: 2n = 30 (Sarawak) (Tjan et al., 1986).

All Karyotype Records for Genus

Explore Data: All, Drilldown
Click here to show/hide karyotype data.
Taxon Haploid Diploid Karyotype Locality Source Notes
Pseudolasius 30 Indonesia Imai et al., 1985
Pseudolasius 30 Sarawak Tjan et al., 1986
Pseudolasius 14 Taiwan Hung et al., 1972 near ''Pseudolasius emeryi''
Pseudolasius 15 30 Malaysia Imai et al., 1983 B Chromosome polymorphism
Pseudolasius 17 30 Malaysia Imai et al., 1983 B Chromosome polymorphism
Pseudolasius 19 30 Malaysia Imai et al., 1983 B Chromosome polymorphism
Pseudolasius 8 Malaysia Imai et al., 1983


The following information is derived from Barry Bolton's Online Catalogue of the Ants of the World.

  • PSEUDOLASIUS [Formicinae: Plagiolepidini]
    • Pseudolasius Emery, 1887a: 244. Type-species: Formica familiaris, by subsequent designation of Bingham, 1903: 337.
    • Pseudolasius senior synonym of Nesolasius: Bolton, 1994: 50.
  • NESOLASIUS [junior synonym of Pseudolasius]
    • Nesolasius Wheeler, W.M. 1935b: 50 [as subgenus of Pseudolasius]. Type-species: Pseudolasius (Nesolasius) typhlops, by original designation.
    • Nesolasius junior synonym of Pseudolasius: Bolton, 1994: 50.

The polymorphic nature of this genus is well known, but overall this is a fairly heterogeneous group that is in need of taxonomic revision. There are clearly some lineages that have taken a hypogaeic evolutionary route and look quite different from the larger, presumably epigaeic species. (LaPolla et al. 2010)


  • Agosti, D. 1991. Revision of the oriental ant genus Cladomyrma, with an outline of the higher classification of the Formicinae (Hymenoptera: Formicidae). Syst. Entomol. 16: 293-310. (page 296, Pseudolasius in Formicinae, Pseudolasius genus group)
  • Bingham, C. T. 1903. The fauna of British India, including Ceylon and Burma. Hymenoptera, Vol. II. Ants and Cuckoo-wasps. London: Taylor and Francis, 506 pp. (page 337, Type-species: Formica familaris, by subsequent designation)
  • Bolton, B. 1994. Identification guide to the ant genera of the world. Cambridge, Mass.: Harvard University Press, 222 pp. (page 50, Pseudolasius senior synonym of Nesolasius; Pseudolasius in Formicinae, Lasiini)
  • Bolton, B. 2003. Synopsis and Classification of Formicidae. Mem. Am. Entomol. Inst. 71: 370pp (page 106, Pseudolasius in Formicinae, Plagiolepidini)
  • Chapman, J. W.; Capco, S. R. 1951. Check list of the ants (Hymenoptera: Formicidae) of Asia. Monogr. Inst. Sci. Technol. Manila 1: 1-327 (page 203, Pseudolasius in Formicinae, Formicini)
  • Dalla Torre, K. W. von. 1893. Catalogus Hymenopterorum hucusque descriptorum systematicus et synonymicus. Vol. 7. Formicidae (Heterogyna). Leipzig: W. Engelmann, 289 pp. (page 180, Pseudolasius as Camponotinae)
  • Dlussky, G. M.; Fedoseeva, E. B. 1988. Origin and early stages of evolution in ants. Pp. 70-144 in: Ponomarenko, A. G. (ed.) Cretaceous biocenotic crisis and insect evolution. Moskva: Nauka, 232 pp. (page 77, Pseudolasius in Formicinae, Lasiini)
  • Donisthorpe, H. 1943h. A list of the type-species of the genera and subgenera of the Formicidae. [concl.]. Ann. Mag. Nat. Hist. 11(10): 721-737 (page 722, Pseudolasius in Formicinae, Acanthomyopsini)
  • Emery, C. 1887b [1886]. Catalogo delle formiche esistenti nelle collezioni del Museo Civico di Genova. Parte terza. Formiche della regione Indo-Malese e dell'Australia. [part]. Ann. Mus. Civ. Stor. Nat. 24[=(2)(4): 241-256 (page 244, Pseudolasius as genus)
  • Emery, C. 1895l. Die Gattung Dorylus Fab. und die systematische Eintheilung der Formiciden. Zool. Jahrb. Abt. Syst. Geogr. Biol. Tiere 8: 685-778 (page 772, Pseudolasius as Camponotinae, Formicini)
  • Emery, C. 1925d. Hymenoptera. Fam. Formicidae. Subfam. Formicinae. Genera Insectorum 183: 1-302 (page 214, Pseudolasius in Formicinae, Lasiini)
  • Forel, A. 1893b. Sur la classification de la famille des Formicides, avec remarques synonymiques. Ann. Soc. Entomol. Belg. 37: 161-167 (page 165, Pseudolasius as Camponotinae, Formicini)
  • Forel, A. 1912j. Formicides néotropiques. Part VI. 5me sous-famille Camponotinae Forel. Mém. Soc. Entomol. Belg. 20: 59-92 (page 89, Pseudolasius as Camponotinae, Formicini)
  • Forel, A. 1917. Cadre synoptique actuel de la faune universelle des fourmis. Bull. Soc. Vaudoise Sci. Nat. 51: 229-253 (page 249, Pseudolasius as Camponotinae, Formicini)
  • Klimes, P., Borovanska, M., Plowman, N.S., Laponce, M. 2018. How common is trophobiosis with hoppers (Hemiptera: Auchenorrhyncha) inside ant nests (Hymenoptera: Formicidae)? Novel interactions from New Guinea and a worldwide overview. Myrmecological News, 26: 31-45.
  • LaPolla, J.S. 2004b. Taxonomic review of the ant genus Pseudolasius in the Afrotropical region. Journal of the New York Entomological Society 112: 97-105.
  • Malsch A, Kaufmann E, Heckroth H-P, Williams DJ, Maryati M, Maschwitz U. 2001 Continuous transfer of subterranean mealybugs (Hemiptera, Pseudococcidae) by Pseudolasius spp. (Hymenoptera, Formicidae) during colony fission? Insectes Soc. 48, 333–341.
  • Matos-Maraví, P., Clouse, R.M., Sarnat, E.M., Economo, E.P., LaPolla, J.S., Borovanska, M., Rabeling, C., Czekanski-Moir, J., Latumahina, F., Wilson, E.O., Janda, M. 2018. An ant genus-group (Prenolepis) illuminates the biogeography and drivers of insect diversification in the Indo-Pacific. Molecular Phylogenetics and Evolution 123, 16–25 (doi:10.1016/j.ympev.2018.02.007).
  • Menozzi, C. 1924c. Alcune nuove formiche africane. [concl.]. Ann. Mus. Civ. Stor. Nat. "Giacomo Doria" 51: 225-227 (page 226, Key to Afrotropical species (out of date).)
  • Wheeler, G. C.; Wheeler, J. 1985b. A simplified conspectus of the Formicidae. Trans. Am. Entomol. Soc. 111: 255-264 (page 258, Pseudolasius in Formicinae, Formicini)
  • Wheeler, W. M. 1910b. Ants: their structure, development and behavior. New York: Columbia University Press, xxv + 663 pp. (page 143, Pseudolasius as Camponotinae, Formicini)
  • Wheeler, W. M. 1915i [1914]. The ants of the Baltic Amber. Schr. Phys.-Ökon. Ges. Königsb. 55: 1-142 (page 133, Pseudolasius as Camponotinae, Formicini)
  • Wheeler, W. M. 1922i. Ants of the American Museum Congo expedition. A contribution to the myrmecology of Africa. VII. Keys to the genera and subgenera of ants. Bull. Am. Mus. Nat. Hist. 45: 631-710 (page 698, Pseudolasius in Formicinae, Formicini)