Pheidole risii

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Pheidole risii
Scientific classification
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Hymenoptera
Family: Formicidae
Subfamily: Myrmicinae
Tribe: Attini
Genus: Pheidole
Species: P. risii
Binomial name
Pheidole risii
Forel, 1892

Pheidole risii casent0908198 p 1 high.jpg

Pheidole risii casent0908198 d 1 high.jpg

Specimen Labels

Rosumek (2017) assessed trophic resource use and period of activity within the ant community in a southern Brazil Atlantic forest. He found this species was a quintessential generalist.


See the description in the nomenclature section.

Keys including this Species


From Wilson (2003): In addition to the type locality, risii has been recorded from São Paulo, Brazil (Kempf 1972b).

Distribution based on Regional Taxon Lists

Neotropical Region: Argentina (type locality), Brazil.

Distribution based on AntMaps


Distribution based on AntWeb specimens

Check data from AntWeb






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

  • risii. Pheidole risii Forel, 1892a: 38 (s.w.q.m.) ARGENTINA. See also: Wilson, 2003: 740.

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


From Wilson (2003): DIAGNOSIS Similar in various traits to Pheidole aper, Pheidole bambusarum, Pheidole brevicona, Pheidole dyctiota, Pheidole laeviventris, Pheidole lutzi, Pheidole rugatula, Pheidole senilis, Pheidole sigillata, Pheidole trachyderma and Pheidole traini, differing as follows.

Major: shallow antennal scrobes; pilosity along dorsal profile of head dense, with uniform short hairs about as long as Eye Length along the posterior half and much longer hairs along the anterior half; occipital cleft deep; occipital lobes smooth and subangulate; pronotum sparsely carinulate, mostly smooth; propodeal spine very stout, equilaterally triangular; postpetiolar node very broad, 2X broader than petiolar node, and spinose.

Minor: occiput, humeri, and propodeal dorsum rugoreticulate; almost all of head and mesosoma foveolate; occiput broad, concave, and lacking nuchal collar.

MEASUREMENTS (mm) Syntype major: HW 0.96, HL 1.02, SL 0.44, EL 0.12, PW 0.54. Syntype minor: HW 0.66, HL 0.66, SL 0.62, EL 0.12, PW 0.44.

COLOR Major: body reddish yellow except for gaster, which is yellowish brown.

Minor: concolorous dark yellow.

Pheidole risii Wilson 2003.jpg

Figure. Upper: syntype, major. Lower: syntype, minor. Scale bars = 1 mm.

Type Specimen Labels

Type Material

ARGENTINA: Buenos Aires, col. Fr. Ris. Musee d'Histoire Naturelle Genève and Museum of Comparative Zoology - as reported in Wilson (2003)


Named after the collector, Fr. Ris. (Wilson 2003)


  • Forel, A. 1892a. Notes myrmécologiques. Ann. Soc. Entomol. Belg. 36: 38-43 (page 38, soldier, worker, queen, male described)
  • Kempf, W. W. 1972. Catálogo abreviado das formigas da região Neotropical. Stud. Entomol. 15: 3–344.
  • Rosumek, F. B. 2017. Natural History of Ants: What We (do not) Know about Trophic and Temporal Niches of Neotropical Species. Sociobiology. 64:244-255. doi:10.13102/sociobiology.v64i3.1623
  • Wilson, E. O. 2003. Pheidole in the New World: A dominant, hyperdiverse ant genus. Harvard University Press, Cambridge, MA. (page 740, fig. major, minor described)