AntWiki: The Ants --- Online
Jump to navigation Jump to search
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
0 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)

  (140 species)

  (30 species)

  (1 species)

  (42 species)

  (19 species)

  (6 species)

  (149 species)

  (66 species)

  (8 species)

  (5 species)

  (9 genera)

  (8 genera)

Gesomyrmex, Oecophylla

  (9 genera)

Gigantiops, Myrmoteras, Santschiella

  (8 genera)

Based on Ward et al. (2016), Matos-Maravi et al. (2018) and Boudinot et al. (2022).

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.

Association with Other Organisms

Species Uncertain

  • An unknown species is a host for the phorid fly Pseudacteon sp. (a parasitoid) (Quevillon, 2018) (encounter mode primary; direct transmission; transmission outside nest).
  • An unknown species is a host for the phorid fly Pseudacteon sp. (a parasite) in Thailand (Brown & Fenner, 1998).

All Associate Records for Genus

Explore Associate Data: All, Drilldown
Click here to show/hide associate data.
Taxon Relationship Associate Type Associate Taxon Associate Relationship Locality Source Notes
Pseudolasius host phorid fly Pseudacteon sp. parasite Thailand Brown & Fenner, 1998
Pseudolasius host phorid fly Pseudacteon sp. parasitoid Quevillon, 2018 encounter mode primary; direct transmission; transmission outside nest

Life History Traits

  • Mean colony size: 325 (Greer et al., 2021)
  • Compound colony type: not parasitic (Greer et al., 2021)
  • Nest site: hypogaeic (Greer et al., 2021)
  • Diet class: herbivore (Greer et al., 2021)
  • Foraging stratum: subterranean/leaf litter (Greer et al., 2021)


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 (5,3 in an undescribed species from Vietnam) • Total dental count: 4-7 • Spur formula: 1 simple, 1 simple; 0, 0 • Eyes: 11-100 ommatidia • Scrobes: absent • Pronotal Spines: absent • Mesonotal Spines: absent • Propodeal Spines: absent • Petiolar Spines: absent • Caste: mostly dimorphic or polymorphic • Sting: absent • Metaplural Gland: present • Cocoon: present


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)