Pheidole jelskii

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)

Identification
See the description in the nomenclature section and the images below.

Distribution
Widespread throughout the West Indies, thence south through South America to southeastern Brazil and northern Argentina. (Wilson 2003)

Distribution based on Regional Taxon Lists
Neotropical Region: Argentina, Barbados, Brazil, Dominican Republic, French Guiana, Greater Antilles, Grenada, Haiti, Paraguay, Saint Lucia, Trinidad and Tobago.

Worker
Minor

Nomenclature

 *  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.

Description
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.'''

Type Material
Cayenne, French Guiana, collected by “M. Jelski”. - as reported in Wilson (2003)

Etymology
Named after the collector, M. Jelski. (Wilson 2003)