Dacetini, Formicidae, Hymenoptera, Insecta, Arthropoda, Animalia
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Line drawing of face view of worker and, at lower right, anterior view of apical fork of mandible (image).
Range
Full Range: throughout mainland tropical America, from southern Mexico to southern Brazil.
Costa Rican Range: Atlantic lowlands, southern Pacific lowlands, upper Pacific slope of Cordillera de Tilaran.
Identification
Mandibles in full-face view linear, elongate and narrow; ventral surface of petiole without spongiform tissue; leading edge of scape with freely projecting hairs, these relatively spatulate and not strongly curved; inner margin of mandible without a tooth or distinctly enlarged denticle at or near the midlength; labral lobes short, trigger hairs at apices of lobes long; outer margins of mandibles relatively straight; mandibles thick, with inner margin convex; close to the apical fork is a small preapical tooth, followed closely by 3-5 smaller denticles; ground pilosity conspicuous and abundant, particularly on head; hairs on head spoon-shaped and reclining; in profile dorsal mesosoma with 4-6 pairs of stout remiform standing hairs (in addition to those at humeri); first gastral sternite finely reticulate to reticulate-punctate at least basally. Also see Bolton (2000:193).
Head length 0.48-0.57mm, mandible length 0.26-0.30, CI 82-87, MI 49-54 (n=20 workers, Bolton 2000).
Similar species: cascanteae, oconitrilloae, paniaguae, gundlachi, eggersi, trieces.
Natural History
Members of the genus are all predaceous, with a static pressure mode of attack (Bolton 1999).
Brown (1960) characterizes the species as follows:
...primarily a species of the leaf litter and upper soil layers in mesic tropical forest. Nests have been found on the underside of a small log buried in leaf litter, in a small pocket in the soil, and among rotting leaves and twigs. In life, the workers are active huntresses ... E. O. Wilson (unpubl. notes) kept a colony from Veracruz alive and gave them a variety of small arthropods, among which they accepted as prey entomobryoid Collembola, while ignoring over two days small millipeds, Reticulitermes nymphs, a small isopod, and an undetermined soft-bodied mite. The colonies so far found have contained from about 20 to 90 workers and one or more queens.
In Costa Rica this species appears relatively common in lowland moist to wet forest.
Selected Records
Winkler samples from road to Monteverde at 900m (islolated patch of evergreen forest in ravine), Carara, Manuel Antonio National Park, Osa Peninsula (Rancho Quemado), Corcovado National Park (Sirena), 19km S Ciudad Neily, La Selva Biological Station.
Comments
Intensive collecting at La Selva Biological Station and the Barva Transect has revealed a complex of five closely similar but consistently separable species related to P. subedentata (Longino 2006). Pyramica subedentata occurs throughout the Neotropics, usually in lowland wet to somewhat seasonal sites, in both mature and second growth forests. It is often collected in samples of litter and rotten wood from the forest floor. Pyramica trieces occurs on the Atlantic slope of Central America from Nicaragua to Panama, from sea level to 1100 m elevation. It occurs most abundantly in mature wet forest where, like P. subedentata, it inhabits leaf litter and rotten wood on the forest floor. Pyramica oconitrilloae, P. cascanteae, and P. paniaguae occur as a graded series of elevational specialists, with P. oconitrilloae occurring at La Selva and the 300 m site on the Barva Transect, P. cascanteae occurring at the 300 m site and at a 600 m site in the nearby Arenal National Park, and P. paniaguae occurring at the 500m, 1100m, and 1500m sites on the Barva Transect. These three all show a tendency to be arboreal, nesting under bark flaps or epiphytes and rarely occurring in samples of litter and rotten wood from the forest floor. A sixth species in this complex, P. connectens, occurs in Colombia and Ecuador.
Original Description
Strumigenys subedentata Mayr 1887:570 (in key), 575. Syntype worker: Brazil, Santa Catarina (Hetscko) [NMV, BMNH].
Later moved to Pyramica. See Bolton (2000) for complete synonymy.
Literature Cited
Bolton, B. 1999. Ant genera of the tribe Dacetonini (Hymenoptera: Formicidae). J. Nat. Hist. 33:1639-1689.
Bolton, B. 2000. The ant tribe Dacetini, with a revision of the Strumigenys species of the Malagasy Region by Brian L. Fisher, and a revision of the Austral epopostrumiform genera by Steven O. Shattuck. Memoirs of the American Entomological Institute 65:1-1028.
Brown, W. L., Jr. 1960 (1959). The neotropical species of the ant genus Strumigenys Fr. Smith: Group of gundlachi (Roger). Psyche 66:37-52.
Longino, J. T. 2006. New species and nomenclatural changes for the Costa Rican ant fauna (Hymenoptera: Formicidae). Myrmecologische Nachrichten 8:131-143.
Mayr, G. 1887. Sudamerikanische Formiciden. Verh. K-K. Zool.-Bot. Ges. Wien 37:511-632.
Page author:
John T. Longino, The Evergreen State College, Olympia WA 98505 USA.longinoj@evergreen.edu
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