Solenopsis rugiceps

Workers were collected in surface and subterranean baits containing Vienna sausage, in an old-growth tropical rainforest.

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

Pacheco and Mackay (2013) – Worker - This species is golden brown with the gaster being darker brown. The relatively coarsely sculptured head of the worker easily separates this species from most other New World species. The rugulae cover much of the anterior part of the head and sides of the head, the posterior part of the head may be moderately smooth and glossy. The four teeth on the anterior border of the clypeus are well developed, the extralateral teeth are nearly as large as the lateral pair of teeth.

The workers of Solenopsis rugiceps are superficially similar only to Solenopsis vinsoni, a species found from Mexico to Panama. These two species are the only ones in the New World that have sculptured heads. Solenopsis rugiceps is apparently monomorphic while S. vinsoni is dimorphic and the major of S. vinsoni may be confused with the workers of S. rugiceps. However, the major worker of S. vinsoni can be easily separated by the sculptured mesosoma, petiole and postpetiole (predominantly smooth and glossy in S. rugiceps). Additionally the notopropodeal suture is weakly depressed (strongly depressed in S. rugiceps). Although the sculpturing of the head is similar in the two species, they do not appear to be closely related.

Distribution based on Regional Taxon Lists
Neotropical Region: Colombia.

Castes
Known only from the worker caste.

Nomenclature

 *  rugiceps. Solenopsis rugiceps Mayr, 1870a: 406 (w.) COLOMBIA.

Worker
Pacheco and Mackay (2013) - Measurements (n=5). TL 1.74-1.80 (1.77); HL 0.558-0.570 (0.566); HW 0.444-0.468 (0.461); EL 0.042; ED 0.036; SL 0.402-0.420 (0.408); FSL 0.168-0.180 (0.177); CI 79.6-82.9 (81.4); SI 71.3-73.7 (72.0); PL 0.096; PW 0.132-0.150 (0.145); PI 64.0-72.7 (66.3); PPL 0.108-0.120 (0.113); PPW 0.150-0.162 (0.157); PPI 66.7-76.9 (71.8); WL 0.402-0.420 (0.416); PSL 0.036-0.042 (0.038); PSW 0.030-0.036 (0.034).

Golden brown with gaster darker brown; head coarsely sculptured, with rugulae covering anterior part of head, sides of head, posterior part may be moderately smooth and glossy; lateral clypeal teeth well developed, extralateral teeth well developed, nearly as large as lateral pair; clypeal carinae well defined; scape nearly extends to posterior margin of head; notopropodeal suture deeply depressed, groove breaks sculpture of mesosoma; petiole broad when viewed in profile, postpetiole oval when viewed dorsally; mesopleuron with horizontal striae or may be completely smooth and shiny (variation also found within type series).

Abundantly hairy (erect and suberect hairs) on all body surfaces, from anterior margin of clypeus to dorsum of gaster.

Type Material
Pacheco and Mackay (2013) - Mayr Collection, Colombia, Santa Fe de Bogota (Bogota) (Lindig) (lectotype worker and 4 paralectotype workers [here designated], ). The types were probably collected elsewhere in Colombia and shipped from Bogota, as the type locality seems too cool and of high elevation for this apparently tropical species.