Strumigenys crementa

Occurs in wet forest habitats, in leaf litter on the forest floor.

Identification
A member of the crassicornis complex in the Strumigenys gundlachi group.

Longino (Ants of Costa Rica) - Mandibles in full-face view linear, elongate and narrow; ventral surface of petiole without spongiform tissue; leading edge of scape with freely projecting hairs; inner margin of mandible with a clearly defined submedian tooth near the midlength; labral lobes long, trigger hairs at apices of lobes short; preapical denticles gradually decreasing in size; mandibles relatively short (MI 33-45); propodeal suture moderately impressed; total head length less than 0.90mm; eyes relatively small, with 14 or fewer ommatidia, with 2-4 in longest row; head in full-face view relatively broad, CI 74-81; in profile head not strongly dorsoventrally flattened, the maximum depth of the head capsule 0.45-0.52 x head length; color red-brown to dark brown; pair of mesonotal setae conspicuous, often erect or tilted forward; erect hairs on first gastral tergite simple, acute or blunt apicaly but not remiform nor flattened and expanded apically; backcurved pair of stout hairs located posteriorly on petiole dorsum slender, scarcely thicker apically than basally; scape relatively short, SI 48-52.

Bolton described this species as "an extra-large version of Strumigenys brevicornis," and stated "I record this as a separate species with some trepidation as its close relationship with brevicornis is obvious." The characters are those of brevicornis, except larger size, relatively shorter scapes, and larger eyes.

Distribution based on Regional Taxon Lists
Neotropical Region: Costa Rica, Honduras, Panama.

Nomenclature

 *  crementa. Pyramica crementa Bolton, 2000: 182 (w.) COSTA RICA. Combination in Strumigenys: Baroni Urbani & De Andrade, 2007: 118

I record this as a separate species with some trepidation as its close relationship with Strumigenys brevicornis is obvious. However, none of the many samples of brevicornis examined is as large as Strumigenys crementa, and none has such large eyes nor the same petiolar and gastral pilosity. Perhaps new collections will eventually bridge the apparent gap between the two, but for the present I consider it best to regard them as distinct species.

I currently refer the Panama material mentioned here to crementa. It consists of a single worker (MCZ) that is larger and darker in colour than known specimens from Costa Rica (HL 0.68, HW 0.54, CI 79, ML 0.34, MI 50, SL 0.28, SI 52, PW 0.38, AL 0.74). Many species have a larger, darker form that seems to be a function of altitude distribution, but so little material of crementa is known that this specimen should be re-examined when crementa itself is better understood.

Worker
HOLOTYPE. TL 2.4, HL 0.61, HW 0.46, CI 75, ML 0.28, MI 46, SL 0.24, SI 52, PW 0.32, AL 0.64. Characters of crassicornis complex. Mandible with 5 – 6 denticles between apicodorsal tooth and submedian tooth, with 1 - 3 minute denticles proximal of the submedian tooth. Eye with 4 ommatidia in the longest row, with 12 – 13 ommatidia in total. Basically crementa appears to be an extra-large version of brevicornis, but with shorter scapes (compare measurements). Morphologically the two are very similar but in crementa the labral lobes are longer and the erect hairs on the first gastral tergite are simple. The backcurved pair of stout hairs located posteriorly on the petiole dorsum are slender, scarcely thicker apically than basally. In brevicornis hairs on the first tergite are stoutly remiform or distinctly flattened and expanded apically; those on the petiole node dorsum are thickly remiform.

PARATYPE. TL 2.3, HL 0.62, HW 0.46, CI 74, ML 0.28, MI 45, SL 0.22, SI 48, PW 0.31, AL 0.62.

Type Material
Holotype worker, Costa Rica: Provo Alajuela, Cordillera de Tilaran, Res. For. de San Ramon, ca 750 m., iii.1990 (P.M. Hammond) (BMNH).

Paratype. 1 worker with same data as holotype.

References based on Global Ant Biodiversity Informatics

 * Dattilo W. et al. 2019. MEXICO ANTS: incidence and abundance along the Nearctic-Neotropical interface. Ecology https://doi.org/10.1002/ecy.2944
 * Fernández, F. and S. Sendoya. 2004. Lista de las hormigas neotropicales. Biota Colombiana Volume 5, Number 1.
 * García-Martínez M. A., J. E. Valenzuela-González, D. L. Martínez-Tlapa , and L. N. Quiroz-Robledo. 2013. New Ant Species (Hymenoptera: Formicidae) Records for Veracruz State and Mexico. Southwestern Entomologist 38(4): 661-666.
 * Longino J. T. 2013. Ants of Nicargua. Consulted on 18 Jan 2013. https://sites.google.com/site/longinollama/reports/ants-of-nicaragua
 * 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. T., and R. K. Colwell. 2011. Density compensation, species composition, and richness of ants on a neotropical elevational gradient. Ecosphere 2(3): 16pp.
 * Longino J. et al. ADMAC project. Accessed on March 24th 2017 at https://sites.google.com/site/admacsite/
 * 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.