P. jelskii is a species that nests in bare soil and open spaces. As such it is well adapted to disturbed habitats of all kinds, from cultivated fields to pastures to roadsides, as well as marginal natural environments such as beaches and river banks. In many places it is extremely abundant, although colony densities vary locally. In the early 1890s H. H. Smith (in Forel 1893j) encountered it only twice on St. Vincent, which given the intensity of his collecting, suggests relative rarity, whereas in the 1990s Stefan Cover and I found it ubiquitous and in dense populations in the nearby islands of Grenada and Barbados. Mature colonies are large, with worker populations numbering into the many hundreds or even thousands. They typically construct conspicuous crater nests with slit-shaped entrances in open soil, but also less regular nests with irregular entrances in vertical banks of soil in heavily disturbed locations. The minors forage singly over distances of up to ten meters or more, and are extremely swift and efficient at laying odor trails over even very loose soil to recruit other minors as well as majors to dead insects and sugar baits. The majors release a strong fetid odor, possibly from skatole, when the colonies are disturbed. (Wilson 2003)
Keys including this Species
Widespread throughout the West Indies, thence south through South America to southeastern Brazil and northern Argentina. (Wilson 2003)
Distribution based on Regional Taxon Lists
Distribution based on AntMaps
Distribution based on AntWeb specimens
Check data from AntWeb
Wheeler (1905), Bahamas - This species is carnivorous. Its nests are flat moundlets, about four inches in diameter, built in sandy, grassy places. The soldiers have the rank odor so characteristic of the ants belonging to the genus Eciton.
The following information is derived from Barry Bolton's New General Catalogue, a catalogue of the world's ants.
- jelskii. Pheidole jelskii Mayr, 1884: 34 (s.w.) FRENCH GUIANA. Forel, 1893g: 400 (q.m.). Subspecies of fallax: Forel, 1893g: 400. Raised to species: Emery, 1894g: 390. Subspecies of fallax: Emery, 1906c: 155; Forel, 1912f: 221. Raised to species, senior synonym of antillensis, arenicola, emiliae and material of the unavailable name retifera referred here: Wilson, 2003: 306.
- arenicola. Pheidole jelskii var. arenicola Emery, 1894g: 390 (footnote) (s.w.) BRAZIL. Subspecies of fallax: Forel, 1908c: 370; Santschi, 1923d: 58. Junior synonym of jelskii: Wilson, 2003: 307.
- antillensis. Pheidole jelskii var. antillensis Forel, 1901e: 356 (s.) ANTILLES. Subspecies of fallax: Bolton, 1995b: 317. Junior synonym of jelskii: Wilson, 2003: 307.
- emiliae. Pheidole fallax r. emiliae Forel, 1901e: 352 (s.w.q.) BRAZIL. Junior synonym of jelskii: Wilson, 2003: 307.
Unless otherwise noted the text for the remainder of this section is reported from the publication that includes the original description.
See the extensive discussion by Wetterer et al. (2015) in the identification section of Pheidole obscurithorax
From Wilson (2003): A member of the fallax group, similar to Pheidole fallax, Pheidole obscurithorax, Pheidole puttemansi, Pheidole roushae, Pheidole tobini and Pheidole valens, and especially the common and widespread fallax, with which it is easily confused.
Major: posterior half of dorsal surface of head completely carinulate; pronotum transversely carinulate; anterior fourth to third of central strip of first gastral tergite shagreened; head tapered toward occiput in side view, as depicted.
P. jelskii differs from P. fallax as follows and as shown: in major, petiole distinctly lower and descending to the peduncle by a much less concave curve, and scapes longer (Scape Length/Head Width 0.60–0.70 as opposed to 0.50–0.59 in fallax major); and in minor, occiput much narrower and nuchal collar thinner than in fallax.
MEASUREMENTS (mm) Holotype major: HW 1.48, HL 1.54, SL 1.00, EL 0.24, PW 0.80. Minor (Cuzco Amazónico, Madre de Dios, Peru): HW 0.56, HL 0.76, SL 1.00, EL 0.20, PW 0.42.
COLOR Major: body medium reddish brown, mandibles dark reddish brown.
Minor: body and most of appendages dark brown, often almost blackish brown, tarsi and mandibles light brown.
Figure. Upper: unique holotype, major. Lower: minor (Cuzco Amazónico, near Puerto Maldonado, Madre de Dios, Peru, associated with major compared with lectotype). Scale bars = 1 mm.
Cayenne, French Guiana, collected by “M. Jelski”. Naturhistorisches Museum Wien, Vienna - as reported in Wilson (2003)
Named after the collector, M. Jelski. (Wilson 2003)
- Emery, C. 1894h. [Untitled.]. Pp. 373-401 in: Ihering, H. von. Die Ameisen von Rio Grande do Sul. Berl. Entomol. Z. 39:321-447. (page 390, raised to species)
- Emery, C. 1906c . Studi sulle formiche della fauna neotropica. XXVI. Bull. Soc. Entomol. Ital. 37: 107-194 (page 155, subspecies of fallax)
- Forel, A. 1893j. Formicides de l'Antille St. Vincent, récoltées par Mons. H. H. Smith. Trans. Entomol. Soc. Lond. 1893: 333-418 (page 400, queen, male described, Variety of fallax)
- Forel, A. 1912g. Formicides néotropiques. Part III. 3me sous-famille Myrmicinae (suite). Genres Cremastogaster et Pheidole. Mém. Soc. Entomol. Belg. 19: 211-237 (page 221, subspecies of fallax)
- Mayr, G. 1884. [Untitled. Descriptions of eight new species.]. Pp. 31-38 in: Radoszkowsky, O. Fourmis de Cayenne Française. Tr. Rus. Entomol. Obshch. 18:30-39. (page 34, soldier, worker described)
- Wetterer, J. K., J. A. MacGown, and L. A. Calcaterra. 2015. Geographic spread of Pheidole obscurithorax (Hymenoptera: Formicidae). Transactions of the American Entomological Society. 141:222-232. doi:10.3157/061.141.0113
- Wheeler, W. M. 1905c. The ants of the Bahamas, with a list of the known West Indian species. Bull. Am. Mus. Nat. Hist. 21: 79-135
- Wilson, E. O. 2003. Pheidole in the New World: A dominant, hyperdiverse ant genus. Harvard University Press, Cambridge, MA.(page 307, Raised to species: new status, fig. major, minor described, Senior synonym of arenicola, emiliae, antillensis)