Strumigenys crementa

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Strumigenys crementa
Scientific classification
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Hymenoptera
Family: Formicidae
Subfamily: Myrmicinae
Tribe: Attini
Genus: Strumigenys
Species: S. crementa
Binomial name
Strumigenys crementa
(Bolton, 2000)

Strumigenys crementa casent0900187 p 1 high.jpg

Strumigenys crementa casent0900187 d 1 high.jpg

Specimen Labels

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.

Keys including this Species

Distribution

Latitudinal Distribution Pattern

Latitudinal Range: 19.5116667° to 8.433°.

 
North
Temperate
North
Subtropical
Tropical South
Subtropical
South
Temperate

Distribution based on Regional Taxon Lists

Neotropical Region: Costa Rica (type locality), Honduras, Panama.

Distribution based on AntMaps

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Distribution based on AntWeb specimens

Check data from AntWeb

Biology

Strumigenys were once thought to be rare. The development and increased use of litter sampling methods has led to the discovery of a tremendous diversity of species. Many species are specialized predators (e.g. see Strumigenys membranifera and Strumigenys louisianae). Collembola (springtails) and other tiny soil arthropods are typically favored prey. Species with long linear mandibles employ trap-jaws to sieze their stalked prey (see Dacetine trap-jaws). Larvae feed directly on insect prey brought to them by workers. Trophallaxis is rarely practiced. Most species live in the soil, leaf litter, decaying wood or opportunistically move into inhabitable cavities on or under the soil. Colonies are small, typically less than 100 individuals but in some species many hundreds. Moist warm habitats and micro-habitats are preferred. A few better known tramp and otherwise widely ranging species tolerate drier conditions. Foraging is often in the leaf litter and humus. Workers of many species rarely venture above ground or into exposed, open areas. Individuals are typically small, slow moving and cryptic in coloration. When disturbed individuals freeze and remain motionless. Males are not known for a large majority of species.

Castes

Nomenclature

The following information is derived from Barry Bolton's Online Catalogue of the Ants of the World.

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

Unless otherwise noted the text for the remainder of this section is reported from the publication that includes the original description.

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.

Description

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 (Museum of Comparative Zoology).

References

  • Baroni Urbani, C. & De Andrade, M.L. 2007. The ant tribe Dacetini: limits and constituent genera, with descriptions of new species. Annali del Museo Civico di Storia Naturale “G. Doria” 99:1-191.
  • Bolton, B. 2000. The ant tribe Dacetini. Memoirs of the American Entomological Institute. 65:1-1028. (page 182, worker described)

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.