Pseudolasius

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Pseudolasius
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
Diversity
66 species
1 fossil species
(Species Checklist)

Pseudolasius australis casent0106005 profile 1.jpg

Pseudolasius australis

Pseudolasius australis casent0106005 dorsal 1.jpg

Specimen Label

Synonyms
Evolutionary Relationships
Formicinae

Myrmelachistini
  (2 genera)




Lasiini

Cladomyrma
  (13 species)





Lasius
  (123 species)



Myrmecocystus
  (30 species)






Zatania
  (6 species)




Paraparatrechina
  (42 species)



Prenolepis
  (19 species)






Nylanderia
  (147 species)




Pseudolasius
  (66 species)




Euprenolepis
  (8 species)



Paratrechina
  (6 species)











Melophorini
  (9 genera)




Formicini
  (8 genera)





Gesomyrmex, Oecophylla



Plagiolepidini
  (9 genera)





Gigantiops, Myrmoteras, Santschiella



Camponotini
  (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).

Identification

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

Distribution

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

Biology

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.

Castes

Head of worker Side of worker

Major worker of Pseudolasius from Queensland.

Head of worker Side of worker

Minor worker of Pseudolasius from Queensland.

Morphology

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.

Karyotype

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 Karyotype Data: All, Drilldown
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

Nomenclature

The following information is derived from Barry Bolton's New General Catalogue, a catalogue of the world's ants.

  • 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)

References