Solenopsis pilosula

This species nests in the soil and their mating season occurs in July (Wheeler, 1908b).

Identification
A New World thief ant that is a member of the fugax species complex

Pacheco and Mackay (2013) – Worker - The workers are medium sized and dark yellow. The head is longer than wide; the clypeus between the frontal carinae is narrow and the lateral and extralateral clypeal teeth are well developed, thickened and blunt. The frontal carinae are nearly parallel. The mesopleuron is horizontally striated. The petiole is thickened when viewed laterally. Queen - undescribed). The queen is large (6.36 mm total length) and dark yellow. The head is subquadrate with sparse coarse punctures. The lateral and extralateral teeth are blunt. The queen has only few hairs present on body surfaces. The eye is relatively small with a diameter of 0.198 mm. The sides of the petiole and postpetiole are horizontally striated with a flange present ventrally on the petiolar peduncle. Male - The male is large (4.62 mm) and concolorous dark brown in color. What is striking about the male is the head is covered in vertical striae from the frontal lobes laterally and anteriorly to the clypeal margin. The petiolar node is angulate. The sides of the petiole and postpetiole are horizontally striated.

The workers of S. pilosula may be confused with those of Solenopsis krockowi, as both species are relatively large and have coarse cephalic punctures. The widely diverging clypeal carinae found in S. krockowi separate it from S. pilosula, in which the carinae are nearly parallel and closely placed.

Both S. pilosula and S. krockowi have queens that are large at nearly 7.0 mm in total length. The queen of S. pilosula can be distinguished from that of S. krockowi in that it is nearly devoid of pilosity with only a few hairs present on all body surfaces (S. krockowi is abundantly hairy). Although both species have four clypeal teeth, those with S. pilosula are blunt, while S. krockowi has sharp teeth. Additionally, S. krockowi has numerous coarse cephalic punctures that are sparsely punctate in S. pilosula. Although the petiole and postpetiole of both species are horizontally striated, only S. pilosula has a thin flange ventrally on the petiolar peduncle.

Keys

 * Key to New World Solenopsis Species Complexes
 * Key to Solenopsis fugax species complex / Clave a las obreras del complejo Solenopsis fugax

Distribution based on Regional Taxon Lists
Nearctic Region: United States. Neotropical Region: Mexico.

Nomenclature

 *  pilosula. Solenopsis pilosula Wheeler, W.M. 1908e: 426, pl. 26, figs. 26, 27 (w.m.) U.S.A.

Worker
Pacheco and Mackay (2013) - Measurements (n=5). TL 2.16-2.52 (2.30); HL 0.600-0.636 (0.619); HW 0.528-0.600 (0.563); EL 0.042; ED 0.042; SL 0.330-0.348 (0.336); FSL 0.150-0.162 (0.155); CI 88.0-95.2 (90.9); SI 52.4-55.2 (54.3); PL 0.132-0.150 (0.144); PW 0.204-0.240 (0.226); PI 62.5-67.6 (63.9); PPL 0.162-0.174 (0.164); PPW 0.222-0.240 (0.227); PPI 71.1-72.9 (72.5); WL 0.480-0.540 (0.516); PSL 0.042-0.048 (0.043); PSW 0.036-0.048 (0.038).

Large; concolorous dark yellow; head subquadrate, longer than wide, coarsely punctate; lateral and extralateral clypeal teeth well developed, thickened and blunt; clypeal carinae well defined, nearly parallel; eyes small, with 3-5 ommatidia; scape short, barely surpasses half-length of head; minor funicular segments 3-8 long; pronotum coarsely punctate, smooth and shiny between punctures; mesopleuron horizontally striated; notopropodeal suture depressed, groove breaks sculpture of mesosoma; metapleuron horizontally striated; mesonotum narrow when viewed dorsally; propodeal spiracle large; posterior propodeal margin angulate (viewed laterally); petiole and postpetiole thickened, nearly of equal width (viewed laterally); petiolar peduncle with well-developed tooth ventrally.

Hairy, pilosity yellow; head covered with erect hairs of equal lengths projecting from coarse punctures, centerline free of hairs; erect and suberect hairs of various lengths on remainder of body, including petiole and postpetiole.

Queen
Pacheco and Mackay (2013) - Measurements (n=1). TL 6.36; HL 0.900; HW 0.882; EL 0.240; ED 0.198; MOL 0.078; MOD 0.084; SL 0.558; FSL 0.30; CI 98.0; SI 62.0; PSL 0.090; PSW 0.080; PL 0.180; PW 0.468; PI 38.5; PPL 0.300; PPW 0.528; PPI 56.8; WL 1.44.

Large; concolorous dark yellow; head rectangular, nearly has wide as long, coarsely punctate; lateral and extralateral clypeal teeth blunt; clypeal carinae well defined; frontal lobes vertically striated; eyes, small black; medial ocellus small, without pigment; mesosoma smooth and shiny, with coarse punctures dorsally; metapleuron horizontally striated; petiole and postpetiole horizontally striated; petiolar node thickened, triangular, with peduncular flange ventrally; postpetiolar node thickened, semicircular, lacking tooth or flange ventrally.

Nearly depilose, pilosity yellow; few scattered erect and suberect hairs on body surfaces.

Male
Pacheco and Mackay (2013) - Measurements (n=2). TL 4.56-4.68 (4.62); HL 0.582-0.600 (0.591); HW 0.618; EL 0.270; ED 0.228; MOL 0.078; MOD 0.084-0.090 (0.087); SL 0.240; FSL 0.960; CI 103-106 (104); SI 40.0-41.2 (40.6); PSL 0.132; PSW 0.120; PL 0.120; PW 0.330-0.342 (0.336); PI 35.1-36.4 (35.7); PPL 0.240; PPW 0.390; PPI 61.5; WL 1.14.

Large; concolorous dark brown, lighter brown appendages; head wider than long; clypeal margin straight, lacking teeth; frontal lobes vertically striated towards medial ocellus, laterally toward eye, anteriorly to clypeal margin; eyes large, black; medial ocellus large, without pigment; pronotum coarsely punctate, smooth and shiny between punctures; propodeal spiracle large; propodeum with striae and roughened sculpturing; petiolar node angulate, with striae and roughened sculpturing; postpetiolar node rounded, semicircular, with striae and roughened sculpturing.

Abundantly hairy, pilosity white and yellow; suberect hairs of equal lengths on pronotum (0.120 mm), curve posteriorly; hairs on petiole and postpetiole curve posteriorly.

Male
Pacheco and Mackay (2013) - Measurements (n=2). TL 4.56-4.68 (4.62); HL 0.582-0.600 (0.591); HW 0.618; EL 0.270; ED 0.228; MOL 0.078; MOD 0.084-0.090 (0.087); SL 0.240; FSL 0.960; CI 103-106 (104); SI 40.0-41.2 (40.6); PSL 0.132; PSW 0.120; PL 0.120; PW 0.330-0.342 (0.336); PI 35.1-36.4 (35.7); PPL 0.240; PPW 0.390; PPI 61.5; WL 1.14.

Large; concolorous dark brown, lighter brown appendages; head wider than long; clypeal margin straight, lacking teeth; frontal lobes vertically striated towards medial ocellus, laterally toward eye, anteriorly to clypeal margin; eyes large, black; medial ocellus large, without pigment; pronotum coarsely punctate, smooth and shiny between punctures; propodeal spiracle large; propodeum with striae and roughened sculpturing; petiolar node angulate, with striae and roughened sculpturing; postpetiolar node rounded, semicircular, with striae and roughened sculpturing.

Abundantly hairy, pilosity white and yellow; suberect hairs of equal lengths on pronotum (0.120 mm), curve posteriorly; hairs on petiole and postpetiole curve posteriorly.

Type Material
Pacheco and Mackay (2013) - Texas, Alice Co., 16-vi-1903 (lectotype worker, 2 paralectotype workers and 3 paralectotype males [here designated], cotype#1-6 20909 ); Texas, Alice, 6-vi-1903 (3 cotype workers ).