Pogonomyrmex salinus worker.

The range of Pogonomyrmex salinus includes (at least some portions of) the states of California, Utah, Nevada, Wyoming, Montana, Oregon, Washington, and Idaho, in the US, and the southern portions of British Columbia, Alberta, and Saskatchewan in Canada. Aside from extreme southern Oregon, this is the only Pogo found in the Pacific Northwest, USA (Oregon & Washington states).

P.salinus can be quite variable in its appearance, external nest structure, and in some behaviors. This ant is referred to as P.owyheei, and/or P.occidentalis in older publications (see below).

Typical length of worker ranges from 5.0mm to 7.0mm, and color varies from light orange-red, to a much darker red, or a brownish-red. Colonies can contain over 6,000 workers, but in most cases, probably have a population of less than 3,000.

Pogonomyrmex salinus was first described by O. Wilfred Olsen in 1934. The species description was based on a single ant collected in August of 1932, by a Mr. E. C. Jaeger, near Bridgeport, California. The distribution/range of this ant was considered to be confined to some parts of eastern California, most of Nevada, and into southeastern Oregon - this did not include the Pogo populations to north.

In 1987, S.O. Shattuck determined that the more northern Pogos (in Oregon, Washington, Idaho, Montana, and on up into Canada - that at various points had been considered to be P.occidentalis, or P.owyheei), and the 'original' P.salinus ants to the south, were all members of one variable species: Pogonomyrmex salinus.

The specific name 'salinus' refers to a saline (salty) area, presumably Soda Springs, near Bridgeport, CA - where the original specimen was collected in 1932.

P.salinus bears a strong superficial resemblance to P.occidentalis, a closely related Pogo.

In the areas where the ranges of P.salinus and P.occidentalis overlap (or in a transitional zone), it can be extremely difficult to know which ant you are looking at. Both species are somewhat variable in their hue - ranging from lighter to darker shades of red (or even orangey red, or reddish brown). While P.occidentalis may have a slightly larger average size, we have seen a few nests where most individuals were as small, or smaller than typical, or larger P.salinus workers (P.occidentalis = 6.5 to 8.5mm length / P.salinus = 5.0 to 7.0mm length Taber 1998).

Nest structure is also unreliable in the differentiation of these species, as the gravel-covered mounds of these two ants can be indistinguishable.

The easiest way to tell these two species apart is by looking at the first 'tooth' at the 'top' of the mandible. This is the basal mandibular tooth, and in P. occidentalis, it is distinctly offset ( i.e., turned up) from the basal mandibular margin. In P. salinus it is not offset, but forms a straight angle with the margin. [see image below - white circles indicate the left basal mandibular teeth]

P.occidentalis and P.salinus - showing offset basal mandibular tooth.

[IMAGE - TOP: P.salinus worker in central Washington state, USA / IMAGE - BOTTOM: P.occidentalis and P.salinus workers in northern Nevada, USA] [scroll down for additional note/references]

References for entire page :

·Cole, A.C. 1966. Ants of the Nevada Test Site. Brigham Young University Science Bulletin, Biological Series - Vol. VII, Number 3, June 1966
·Cole, A.C. 1968. Pogonomyrmex Harvester Ants: A Study of the Genus in North America. Knoxville, University of Tennessee Press
·Olsen, O.W. 1934. No. 8 - Notes on the North American Harvesting Ants of the Genus Pogonomyrmex Mayr. Cambridge, Mass. Bulletin of the Museum of Comparative Zoology at Harvard College, Vol. LXXVI, No. 8
·Porter, S.D., and C.D. Jorgensen. 1981. Foragers of the Harvester Ant, Pogonomyrmex owyheei: a Disposable Caste? Behavioral Ecology and Socialbiology (1981) 9:247-256
·Shattuck, S.O. 1987. An Analysis of Geographic Variation in the Pogonomyrmex occidentalis Complex (Hymenoptera: Formicidae) Psyche Vol. 94
·Smith, M.R. 1953. Pogonomyrmex salinus Olsen, a Synonym of Pogonomyrmex occidentalis (Cress.) (Hymenoptera: Formicidae). Reprinted from Bulletin of the Brooklyn Entomological Society Vol. XLVIII, No. 5, pp 131-132. December 1953.
·Taber, S.W. 1998. The World of the Harvester Ants. College Station, TX, Texas A&M University Press