Stenamma smithi

AntWiki: The Ants --- Online
Jump to navigation Jump to search
Stenamma smithi
Scientific classification
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Hymenoptera
Family: Formicidae
Subfamily: Myrmicinae
Tribe: Stenammini
Genus: Stenamma
Species: S. smithi
Binomial name
Stenamma smithi
Cole, 1966

Stenamma smithi casent0005822 profile 1.jpg

Stenamma smithi casent0005822 dorsal 1.jpg

Specimen labels


A mature nest of Stenamma smithi has never been found. The types and most other samples are from traps, litter samples or consist of stray workers. A synonyomized speices (Stenamma knowltoni Gregg (1972)) was described from a queen and four workers collected from "mossy sage duff." Habitats where this ant has been found include shrub steppe, sierran meadow, and xeric areas containing sage.


The median lobe projects beyond the apical margin of the clypeus, and there is a distinct transverse carinula at the summit of the declivity so that in frontal view the median lobe appears to be truncate. In profile the declivitous face of the median lobe is concave.

Eye size is variable and appears to be correlated with overall size. The number of ommatidia in the greatest diameter of the eye varies from 8-12 and the distance from the lower eye margin to the mandibular insertion is from 1.3-1.5 times the eye length. This distance is proportionately greater in small specimens.

The metanotal impression seems always to be long, as noted by Cole, shallowest in small specimens, most pronounced in the largest. The transverse median welt within the impression, noted and figured by Cole, seems to be of rare occurrence. It is absent from many specimens (including the two paratypes studied) and barely discernible in most. Seldom is it distinct and I doubt that it can be of any importance as a diagnostic character.

Among the western species of Stenamma, the workers of Stenamma smithi may be separated from most by the combination of large eyes, short oculo-mandibular distance, form of the median clypeallobe, long basal face of the propodeum and polished first tergite and sternite. The relatively large eyes and structure of the median clypeal lobe and of the propodeum are shared with two other species: Stenamma punctatoventre and Stenamma chiricahua. The first of these, however, possesses distinctly sculptured first tergite and first sternite. Separation from Stenamma chiricahua is not such a simple matter and I have thus far not been successful in working out a reliable method.

As a rule, the eyes of Stenamma smithi are larger, with from 8-12 facets in greatest diameter and the oculo-mandibular distance is from 0.8-l.l times the eye length. There are, however, some unusually small specimens with five or six facets in the greatest eye diameter and the oculo mandibular distance is from 1.2-1.5 times the eye length. Of 40 specimens examined at random, 30% fall into this range, and thus lap into the range given for Stenamma chiricahua. These small specimens, while very similar to Stenamma chiricahua, usually lack definite longitudinal rugulae on the upper half of the side of the propodeum. In Stenamma smithi this area is more often moderately shiny and closely, finely punctulate.

The transverse metanotal groove of Stenamma smithi is most often deeply impressed, the sides straight; the groove, in profile view, is longer than deep, the bottom flat. In Stenamma chiricahua the groove is much narrower, notch-like in profile with oblique sides.

Snelling 1973


Distribution based on Regional Taxon Lists

Nearctic Region: United States (type locality).

Distribution based on AntMaps


Distribution based on AntWeb specimens

Check data from AntWeb


USA. Known from California, Idaho, Nevada, Oregon and Utah.



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

  • smithi. Stenamma smithi Cole, 1966: 7, fig. (w.) U.S.A. Senior synonym of knowltoni: Snelling, R.R. 1973c: 12.
  • knowltoni. Stenamma knowltoni Gregg, 1972: 35, fig. 1 (w.q.) U.S.A. Junior synonym of smithi: Snelling, R.R. 1973c: 12.

Type Material

The holotype and one paratype will be deposited in the U. S. National Museum; other paratypes will be deposited in the Museum of Comparative Zoology and in the author's collection.

Type Locality Information

Atomic Energy Commission Nevada Test Site near Mercury, Nevada.


Patronym. I am pleased to name this interesting new species for Dr. M. R. Smith, my good friend and colleague.


  • Cole, A. C., Jr. 1966b. Ants of the Nevada Test Site. Brigham Young Univ. Sci. Bull. Biol. Ser. 7(3 3: 1-27 (page 7, fig. worker described)
  • Gregg, R. E. 1972. A new species of Stenamma (Hymenoptera: Formicidae) from Utah. Great Basin Naturalist. 32:35-39.
  • Snelling, R. R. 1973. Studies on California ants. 7. The genus Stenamma (Hymenoptera: Formicidae). Contributions in Science (Los Angeles). 245:1-38. (page 12, Senior synonym of knowltoni)

References based on Global Ant Biodiversity Informatics

  • Allred D. M. 1982. Ants of Utah. The Great Basin Naturalist 42: 415-511.
  • Allred, D.M. 1982. The ants of Utah. Great Basin Naturalist 42:415-511.
  • Branstetter M. G. 2012. Origin and diversification of the cryptic ant genus Stenamma Westwood (Hymenoptera: Formicidae), inferred from multilocus molecular data, biogeography and natural history. Systematic Entomology 37: 478-496.
  • Des Lauriers J., and D. Ikeda. 2017. The ants (Hymenoptera: Formicidae) of the San Gabriel Mountains of Southern California, USA with an annotated list. In: Reynolds R. E. (Ed.) Desert Studies Symposium. California State University Desert Studies Consortium, 342 pp. Pages 264-277.
  • Field Museum Collection, Chicago, Illinois (C. Moreau)
  • Gregg R. E. 1972. A new species of Stenamma (Hymenoptera: Formicidae) from Utah. Great Basin Naturalist 32: 35-39.
  • Hoey-Chamberlain R. V., L. D. Hansen, J. H. Klotz and C. McNeeley. 2010. A survey of the ants of Washington and Surrounding areas in Idaho and Oregon focusing on disturbed sites (Hymenoptera: Formicidae). Sociobiology. 56: 195-207
  • La Rivers I. 1968. A first listing of the ants of Nevada. Biological Society of Nevada, Occasional Papers 17: 1-12.
  • MontBlanc E. M., J. C. Chambers, and P. F. Brussard. 2007. Variation in ant populations with elevation, tree cover, and fire in a Pinyon-Juniper-dominated watershed. Western North American Naturalist 67(4): 469–491.
  • Snelling R. R. 1973. Studies on California ants. 7. The genus Stenamma (Hymenoptera: Formicidae). Contributions in Science (Los Angeles) 245: 1-38.
  • Wheeler G. C., and J. Wheeler. 1986. The ants of Nevada. Los Angeles: Natural History Museum of Los Angeles County, vii + 138 pp.
  • Wheeler, G.C. and J. Wheeler. 1978. Mountain ants of Nevada. Great Basin Naturalist 35(4):379-396
  • Yensen N. P., W. H. Clark, and A. Francoeur. 1977. A checklist of Idaho ants (Hymenoptera: Formicidae). Pan-Pacific Entomologist 53: 181-187