Wasmannia williamsoni

AntWiki: The Ants --- Online
Wasmannia williamsoni
Scientific classification
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Hymenoptera
Family: Formicidae
Subfamily: Myrmicinae
Tribe: Attini
Genus: Wasmannia
Species: W. williamsoni
Binomial name
Wasmannia williamsoni
Kusnezov, 1952

Wasmannia williamsoni casent0260383 p 1 high.jpg

Wasmannia williamsoni casent0260383 d 1 high.jpg

Specimen Labels

Kusnezov (1952) described the Wasmannia fauna of Argentina, and Wasmannia sulcaticeps and Wasmannia williamsoni were described as having an allopatric distribution. Wasmannia sulcaticeps occurred in more humid environments near Buenos Aires and in the northern provinces of Tucuman, Salta, and Jujuy. Wasmannia williamsoni occurred in the more arid habitats west of Buenos Aires. (Longino & Fernández 2007)


Wasmannia williamsoni has the largest workers in the genus, based on the one worker we have examined. It is far larger than any other Wasmannia worker we have seen. Wasmannia sulcaticeps and Wasmannia williamsoni are two related species that occur at the far southern limit of the genus, in Argentina. They are both distinguished from other members of the genus by the heavy striate sculpture on the face and by the very small propodeal spiracle. (Longino & Fernández 2007)

Keys including this Species


Latitudinal Distribution Pattern

Latitudinal Range: -30.069722° to -37.12°.

Tropical South

Distribution based on Regional Taxon Lists

Neotropical Region: Argentina (type locality).

Distribution based on AntMaps


Distribution based on AntWeb specimens

Check data from AntWeb

Countries Occupied

Number of countries occupied by this species based on AntWiki Regional Taxon Lists. In general, fewer countries occupied indicates a narrower range, while more countries indicates a more widespread species.

Estimated Abundance

Relative abundance based on number of AntMaps records per species (this species within the purple bar). Fewer records (to the left) indicates a less abundant/encountered species while more records (to the right) indicates more abundant/encountered species.


Cuezzo et al. (2015) - This species was only known from its type locality in Castex (Espinal ecoregion), La Pampa, in central Argentina. A new survey was conducted during 2011 to search for its presence in Buenos Aires and La Pampa provinces. However, its presence could only be confirmed 59 years after its discovery by a small colony found under a stone next to a Caldén tree (Prosopis caldenia) scrubland in Castex. The collecting site was located in the ecotone between the Pampeana and Espinal ecoregions. Unfortunately, gynes or males were not found. In 2012, a few workers of this species were captured by C. Ramos in three pitfall traps placed in Olavarría and Coronel Suárez in southern Buenos Aires and Macachín in western La Pampa province, and by S. Santoandre in six pitfall traps placed between 436-1025 m elevation in the Parque Provincial Ernesto Tornquist, next to the locality of Sierra de la Ventana, also in southern Buenos Aires. A new survey was conducted in these sites in 2013 to try to collect sexuals of this species. Fortunately, two small colonies (one of them containing a queen) were manually found under small stones at 412 and 536 m elevation in the park Tornquist. This protected area is located in the Austral district of the Pampeana ecoregions (Cabrera & Willink,1980). The climate in this mountainous region is temperate, with higher humidity in the inter-mountains areas. Annual rainfall ranges between 500 - 800 mm (De Fina, 1992). The mean temperature in summer and winter is of 20.5 and 8°C, respectively; the absolute maximum temperature in summer is of 40°C, while in winter frosts are frequent and it occasionally snows.


Males have yet to be collected.


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

  • williamsoni. Wasmannia williamsoni Kusnezov, 1952e: 181, figs. 1, 4-7 (w.q.) ARGENTINA.

Unless otherwise noted the text for the remainder of this section is reported from the publication that includes the original description.



Cuezzo et al. (2015) - (n = 20): HL: 0.55-0.60; HW: 0.48-0.53; EL: 0.10-0.13; SL: 0.38-0.43; AD: 0.28-0.35; PSL:0.10- 0.12; WL: 0.50-0.63; PD: 0.10-0.13; PTL: 0.15-0.20; PPTL: 0.10-0.15; PTW: 0.13-0.15; PPTW: 0.18-0.23; CI: 87-88; OI: 18-22.

Reddish-brown with gaster slightly darker than rest of body, sometimes slightly darker than Wasmannia auropunctata. Head in dorsal view with erect, short (<0.05 mm) and abundant setae.

Head between frontal carinae, from posterior margin of the clypeal disc to the frontovertexal margin covered with very regular longitudinal carinae (approx. 10-12). Carinae present in malar space. Disc of clypeus bears more than 6 longitudinal and irregular carinae. Antennal scrobe with a short medial longitudinal carina that barely exceeds posterior margin of compound eye. Ventral margin of antennal scrobe defined by preocular carina that reaches frontovertexal margin. Antennal scape fails to reach frontovertexal margin. Antenna with 11 segments. Compound eye well developed, protruding from lateral margin of head in full face view. Frontovertexal corner bears long, curved seta at each side. Humeral angle acute, strongly developed. Pro- and mesonotum with 8-10 longitudinal carinae. Propleura with four longitudinal carinae and foveolate, sometimes weakly developed, meso and metapleura foveolate, without carinae. Rounded epicnemial process well developed. Dorsal and lateral sides of propodeum foveolate. In lateral view propodeal spine with wide base. Propodeal spine length less than petiole in lateral view. In dorsal view propodeal spine joined by curved line. Metapleural gland well developed and bulky, protruding beyond mesosomal profile. Propodeal lobe well developed, foveolate and almost rectangular with round angles. Short peduncle. Petiole in dorsal view slightly narrower than postpetiole, both heavily foveolate. In lateral view petiolar node rounded. Sterno-postpetiolar process well developed with short spine. Metasomal tergite 3 (fourth abdominal segment) weakly reticulate. Gaster covered with long, weakly curved and sparse hairs.


Cuezzo et al.(2015) - (n = 1).HL: 0.62, HW: 0.57, EL: 0.15, WL: 0.72, CI: 0.91, OI: 0.24.

Dealate. Color dark brown. Head slightly wider behind compound eyes. Scape does not reach vertexal margin. More than 14 longitudinal, strongly marked and irregular striae present between frontal carinae. Antennal scrobe deep and punctuate, crossed longitudinally by preocular carina originating from ventral margin of antennal torulus and almost reaches posterior margin of compound eye. Antennal scrobe delimited ventrally by carina that reaches occipital angle. Well-developed compound eye located closest to anterior margin of head. Antennae with 11 segments, terminal club with 2 antenomeres. Dorsal surface of mandible with 2-3 longitudinal fine striae. Masticatory margin of mandible with five teeth. Discal surface of clypeus with 7-8 well developed longitudinal estriae. Pronotum poorly developed antero-dorsally, scutum in dorsal view encompasses more than half of mesosoma. Humeral angle obtuse, strongly marked. Mesonotum dorsally with irregular and well developed striae. Axilla not well developed. Scutellum poorly developed, punctuate without median longitudinal groove. Anapleural sulcus barely visible, incomplete. Anepisternum, katepisternum and metakatepisternum punctuate. Propodeal spine narrow at base. Propodeal lobe rounded. Cinctus 1 and 2 well-developed. Petiolar peduncle shorter than petiole in lateral view. Sterno-postpetiolar process forms sharp and short spine. Metasomal tergum 3 weakly punctate and covered with sparse and subdecumbent, fine setae.

Type Material

Cuezzo et al. (2015) - Syntype worker. Argentina: La Pampa, General Pico, 07 Jun 1950, #6066, 1 w, N. Kusnezov coll (Fundacion e Instituto Miguel Lillo ).


References based on Global Ant Biodiversity Informatics

  • Diehl-Fleig E. 2014. Termites and Ants from Rio Grande do Sul, Brazil. Sociobiology (in Press).
  • Osorio Rosado J. L, M. G. de Goncalves, W. Drose, E. J. Ely e Silva, R. F. Kruger, and A. Enimar Loeck. 2013. Effect of climatic variables and vine crops on the epigeic ant fauna (Hymenoptera: Formicidae) in the Campanha region, state of Rio Grande do Sul, Brazil. J Insect Conserv 17: 1113-1123.
  • Santoandre S., J. Filloy, G. A. Zurita, and M. I. Bellocq. 2019. Ant taxonomic and functional diversity show differential response to plantation age in two contrasting biomes. Forest Ecology and Management 437: 304-313.