Belize and Honduras south to Amazonian Peru, Trinidad. Costa Rica: Atlantic and southern Pacific lowlands to 500m.
This is a very common species in Costa Rica. It inhabits mature wet forest floor where it nests in dead wood. Workers commonly recruit to baits on the forest floor.
Wilson, E. O.:
Etymology L rugiceps , wrinkle- or crease-headed, denoting the completely carinulate surface of the head.
Diagnosis Major: dorsal surface of the head except for clypeus and frontal triangle completely carinulate and foveolate; sides of the mesosoma and waist foveolate; gaster smooth and shiny; postpetiolar node laterally angulate.
Minor: head other than clypeus and frontal triangle, all of mesosoma, and sides of waist foveolate; occiput narrowed but lacking nuchal collar.
Longino (1997) describes the considerable geographic variation he found within Costa Rica as follows: "the shiny patch on dorsum of promesonotum is most developed on Atlantic slope specimens, is reduced on some Pacific slope specimens (Carara at 500 m, Rancho Quemado on the Osa), and absent on many Pacific slope specimens (Corcovado, Manuel Antonio, Carara at 30 m). Correlated with the reduction of the dorsal shiny spot is a change in color from dark brown to orange." I have placed light reddish brown specimens from the Arima Valley, Trinidad (600-700 m), light reddish brown specimens from Tingo Maria, Huanuco, Amazonian Peru, and reddish yellow ("orange") specimens from Cuzco Amazonico, Madre de Dios, further south in Amazonian Peru, as more farflung geographic variants of the same species.
Measurements (mm) Holotype major: HW 0.90, HL 0.92, SL 0.64, EL 0.14, PW 0.42. Paratype minor: HW 0.44, HL 0.54, SL 0.64, EL 0.10, PW 0.28.
Color Major: type series are dark, almost blackish brown, with a contrasting medium yellow fringe on the anterior rim of the head capsule, as shown; appendages plain medium to brownish yellow.
Minor: in type series, body dark brown except for slightly contrasting narrow anterior strip on the head capsule; scape and legs except tarsi light brown; funiculi and tarsi brownish yellow. Geographic variation that departs from these color patterns is described in the Diagnosis above.
Range Widespread in Costa Rica (Longino 1997), also recorded from Belize, Guatemala, Honduras, Panama, Trinidad, and Amazonian Peru.
Biology Nests in pieces of rotting wood on floor of mature wet forest (in Costa Rica, E. O. Wilson, unpublished and J. T. Longino 1997; and in Cuzco Amazonico, Peru, Stefan Cover). Winged queens were found in a nest at Tingo Maria, Huanuco, Peru, during 9-12 March by W. L. Brown and W. Sherbrooke.
Figure Upper: holotype, major. Above the mesosoma of the holotype is shown the outline of a paratype mesosoma, to illustrate variation in the propodeal angle within the same nest series. Lower: paratype, minor. COSTA RICA: La Selva Biological Station, near Puerto Viejo, Heredia (E. O. Wilson). Scale bars = 1 mm.