Dacetini, Formicidae, Hymenoptera, Insecta, Arthropoda, Animalia
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Range
Full Range: Costa Rica to southern Brazil and Paraguay, but appears largely absent from Amazonia.
Costa Rican Range: lowland to mid-elevation sites on Atlantic and Pacific slopes.
Identification
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 (former Smithistruma); 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 present; ventral surface of petiole in profile with a deep, conspicuous and very obviously spongiform curtain, its maximum depth at least half that of the peduncle and usually more; disc of postpetiole completely unsculptured and glassy smooth; anterior border of clypeus broadly rounded; basal lamella of mandible immediately followed distally by the tooth-row, without a second lamella that extends forward for half the exposed length of the fully closed mandible; mandibles short, MI 19-24; eye with ten or more ommatidia in total; promesonotal dorsum with a fine median longitudinal carina through most or all of its length; pronotal dorsum partially to mostly sculptured; propodeal dorsum weakly to strongly reticulate-punctate; in full-face view anterior clypeal margin transverse to extremely shallowly convex between points where outer margins of fully closed mandibles intersect the clypeal margin; basal tooth-row of mandible consisting only of narrowly triangular high acute teeth; disc of petiole node in dorsal view as long as broad and with the sides of the node converging anteriorly. Also see Bolton (2000:155).
Carara specimens are larger, darker, and with longer propodeal spines than Atlantic slope specimens. I predict this will be a consistent difference between Pacific slope and Atlantic slope material, following a trend of diagnostically distinct forms on the two sides of Costa Rica (pers. obs.).
Similar species: nigrescens, parsauga.
Natural History
Members of the genus are all predaceous, with a static pressure mode of attack (Bolton 1999).
In Costa Rica, this species occurs in wet forest habitats. It is apparently rare and/or difficult to collect. Most collections have been from mid-elevation wet forest (around 500m) on either slope. I have twice collected the species using Winkler bag extraction from sifted forest floor leaf litter. One collection was from Carara and the other from Hitoy Cerere. These were the only occurrences among dozens of sifted litter samples that I have examined from throughout Costa Rica. I also collected a small colony in Braulio Carrillo National Park. It was in a rotten stump at the forest edge.
Original Description
Strumigenys fridericimuelleri Forel 1886:213. Syntype worker: Brazil, [Santa Catarina?] Itajahy (W. Mueller).
Later moved to Smithistruma, then Pyramica. See Bolton (2000) for complete synonymy.
Literature Cited
Bolton, B. 1999. Ant genera of the tribe Dacetonini (Hymenoptera: Formicidae). Journal of Natural History 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.
Forel, A. 1886. Einige Ameisen aus Itajahy (Brasilien). Mitt. Schweiz. Entomol. Ges. 7:210-217.
Page author:
John T. Longino, The Evergreen State College, Olympia WA 98505 USA.longinoj@evergreen.edu
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