Strumigenys depressiceps

Occurs in wet forest habitats. It inhabits leaf litter on the forest floor. I have only seen it from Winkler samples, and one nocturnal forager. (Longino, Ants of Costa Rica)

Identification
Bolton (2000) - A member of the Strumigenys schulzi-group. S. depressiceps was well defined in its original description and succinctly summarised by Brown (1953a). In that publication Brown isolated the species in its own subgenus (Platystruma) because of its extremely flattened head. He later (Brown, 1973a) synonymised this subgenus under Smithistruma and it is now clear that depressiceps is nothing more than a specialised member of the schulzi-group.

The characters described here isolate depressiceps within the group as it is the only known species with a strikingly flattened head, dense stubbly standing pilosity on all dorsal surfaces of head and body, standing dense pilosity on the legs, and an elongate low basal lamella on the mandible.

Longino (Ants of Costa Rica) - Mandibles in side view straight, not broadly curved ventrally; mandibles relatively short, subtriangular, much of the apical portion meeting along a serially toothed masticatory margin when closed; color red-brown; face punctate; sides of posterior half of mesosoma completely and densely punctulate; face and mesosoma with abundant, stiff, short setae (stubble); leading edge of scape with a row of conspicuous projecting curved hairs, of which those distal to the subbasal bend distinctly curve toward the base of the scape; pronotal humeral hair absent; head in profile strongly dorsoventrally flattened; dorsal surfaces of middle and hind tibiae with abundant freely projecting suberect to erect simple hairs.

Distribution based on Regional Taxon Lists
Neotropical Region: Colombia, Costa Rica, Ecuador, Guyana, Honduras, Panama, Peru.

Biology
Brown (1964) - A colony was taken in hollow rotten stick about 1 cm in diameter lying in the leaf litter of wet ravine forest at about 800 m altitude on Cerro Campana, Panama Prov., Panama.

The type material was collected from a cavity in a rotten log.

Nomenclature

 *  depressiceps. Strumigenys (Cephaloxys) depressiceps Weber, 1934a: 47, figs. 6, 14 (w.m.) GUYANA. Combination in Smithistruma (Platystruma): Brown, 1953g: 112; in Pyramica: Bolton, 1999: 1673; in Strumigenys: Baroni Urbani & De Andrade, 2007: 118. See also: Bolton, 2000: 218.

Worker
Bolton (2000) - TL 2.5-2.8, HL 0.77-0.80, HW 0.52-0.58, CI 67-73, ML 0.10-0.12, MI 12-16, SL 0.28-0.31, SI 52-56, PW 0.32-0.36, AL 0.75-0.85 (7 measured).

Basal lamella of mandible a long flat-topped rectangle, its length equal to, or even slightly greater than, the distance separating the apices of teeth 1 and 4 (counting from basal tooth). Head strikingly dorsoventrally flattened, its maximum depth 0.50 X HW or less. In profile the depth of the head at eye level is little more than twice the diameter of the eye. Eye relatively large, with 6-8 ommatidia in the longest row and more than 25 ommatidia in total. Anterior clypeal margin convex. Scape markedly dorsoventrally flattened and broad in dorsal view. Pronotum marginate dorsolaterally. Petiole node in dorsal view longer than broad, in profile its dorsal length much greater than the height of its anterior face. No trace of ventral spongiform tissue on the petiole. Head and body densely and quite coarsely reticulate-punctate on all surfaces except the gaster. All dorsal surfaces of head and body densely clothed with short simple stubbly pilosity that is suberect to erect. Hairs shortest on dorsal head and pronotum, longer on mesonotum and slightly longer still on waist segments and first gastral tergite. Dorsal surfaces of femora, tibiae and basitarsi with numerous similar stubbly suberect hairs. With head in full-face view the dorsolateral margins with numerous freely projecting short hairs. Apicoscrobal hair discernible but scarcely longer than the other projecting hairs. Dorsolateral margin of pronotum with a row of laterally projecting curved hairs; humeral hair not strongly differentiated from them, somewhat longer but by no means obviously distinct.

Type Material
Bolton (2000) - Syntype workers and males, GUIANA: Kartabo, 19.vii.1920 (W.M. Wheeler) [examined].

References based on Global Ant Biodiversity Informatics

 * Basset Y., L. Cizek, P. Cuenoud, R. K. Didham, F. Guilhaumon, O. Missa, V. Novotny, F. Odegaards, T. Roslin, J. Schmidl et al. 2012. Arthropod diversity in a tropical forest. Science 338(6113): 1481-1484.
 * Bolton, B. 2000. The Ant Tribe Dacetini. Memoirs of the American Entomological Institute 65
 * Brown W. L. 1964. The ant genus Smithistruma: a first supplement to the world revision (Hymenoptera: Formicidae). Transactions of the American Entomological Society 89: 183-200.
 * Brown W. L., Jr. 1953. Revisionary studies in the ant tribe Dacetini. Am. Midl. Nat. 50: 1-137.
 * Chacon de Ulloa P., A. M. Osorio-Garica, R. Achury, and C. Bermudez-Rivas. 2012. Hormigas (Hymenoptera: Formicidae) del Bosque seco tropical (Bs-T) de la cuenca alta del rio Cauca, Colombia. Biota Colombiana 13(2): 165-181.
 * Fernández, F. and S. Sendoya. 2004. Lista de las hormigas neotropicales. Biota Colombiana Volume 5, Number 1.
 * Franco W., N. Ladino, J. H. C. Delabie, A. Dejean, J. Orivel, M. Fichaux, S. Groc, M. Leponce, and R. M. Feitosa. 2019. First checklist of the ants (Hymenoptera: Formicidae) of French Guiana. Zootaxa 4674(5): 509-543.
 * Kempf, W.W. 1972. Catalago abreviado das formigas da regiao Neotropical (Hym. Formicidae) Studia Entomologica 15(1-4).
 * Longino J. T. L., and M. G. Branstetter. 2018. The truncated bell: an enigmatic but pervasive elevational diversity pattern in Middle American ants. Ecography 41: 1-12.
 * Longino J. et al. ADMAC project. Accessed on March 24th 2017 at https://sites.google.com/site/admacsite/
 * Silva T. S. R., and R. M. Feitosa. 2019. Using controlled vocabularies in anatomical terminology: A case study with Strumigenys (Hymenoptera: Formicidae). Arthropod Structure and Development 52: 1-26.
 * Sosa-Calvo J., S. O. Shattuck, and T. R. Schultz. 2006. Dacetine ants of Panama: new records and description of a new species. Proceedings of the Entomological Society of Washington 108: 814-821.
 * Weber N. A. 1934. Notes on neotropical ants, including the descriptions of new forms. Revista de Entomologia (Rio de Janeiro) 4: 22-59.