Pyramica nigrescens (Wheeler 1911)

Dacetini, Formicidae, Hymenoptera, Insecta, Arthropoda, Animalia

worker face view

worker lateral view


Full Range: Jamaica, Cuba, Haiti, Dominican Republic, Bahamas, Mexico to Costa Rica, Trinidad.

Costa Rican Range: Guanacaste lowlands, Atlantic coast.


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 of alternating high narrow acutely triangular teeth and lower bluntly rounded broader teeth; tooth four from base particularly broad and rounded; disc of petiole node in dorsal view much broader than long, roughly transversely rectangular, the sides not converging anteriorly. Also see Bolton (2000:157).

Similar species: fridericimuelleri, parsauga.

Natural History

Members of the genus are all predaceous, with a static pressure mode of attack (Bolton 1999).

This species occurs in coastal areas, dry forest, and disturbed habitats. My collections are from Winkler samples of sifted leaf litter. Its geographic distribution and habitat preference suggest it could be a tramp species dispersed by commerce.

Original Description

Strumigenys alberti var. nigrescens Wheeler 1911:28. Syntype worker: Jamaica, Mandeville.

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). 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.

Wheeler, W. M. 1911. Additions to the ant-fauna of Jamaica. Bull. Am. Mus. Nat. Hist. 30:21-29.

Page author:

John T. Longino, The Evergreen State College, Olympia WA 98505

Date of this version: 7 May 2001
Previous versions of this page: 4 March 1997
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