Apterostigma pilosum, almost certainly a complex of many species (see Comments), occurs in forested habitats throughout Costa Rica, from sea level to cloud forest habitats at 1700m. Most examples are workers and queens extracted from Berlese or Winkler samples of sifted leaf litter. In the Bosque Humedo of Santa Rosa National Park I found a nest under a stone. The fungus garden was a spongy mass about 5cm wide. The colony was polygynous, with at least 9 dealate queens. At Estacion Pitilla in the Guanacaste Conservation Area, I found a golf ball-sized nest under rotten wood along a dirt road in second growth forest. At the El Ceibo station along the Barva Transect in Braulio Carrillo National Park, I found a nest under dead wood on ground. The nest space was a disk-shaped area about 4cm across. White hyphae lined the nest and the center was a mass of fuzzy yellow particles. The workers were all immobile on disturbance and very hard to see. They remained motionless for several minutes before beginning to move.
Widespread in Neotropics, from southern Mexico to Argentina. Costa Rica: throughout the country from sea level to 1700m.
Taxonomic history
Mayr, 1887 PDF: 554 (w.).Unresolved Apterostigma pilosum-complex, containing the nominal taxa Apterostigma abdita, Apterostigma discrepans, Apterostigma mayri, Apterostigma moelleri, Apterostigma pallidum, Apterostigma pilosum, Apterostigma scutellare, Apterostigma tramitis, Apterostigma zip: Lattke, 1997 PDF: 165.Alto Paraguay, Alto Paraná , Amambay, Canindeyú , Concepción , Itapúa , Misiones (ALWC, INBP, LACM, MHNG USNM). Literature records: Alto Paraná (Fowler 1981).
