Pogonomyrmex anzensis worker.

The Anza Desert Harvester

Due to its unusual preference for steep, rocky habitat, this Pogo remained an enigma for four and half decades after its initial collection in 1952. [click here to read Gordon Snelling's account of this ant's rediscovery]

The limited known range of P.anzensis, coupled with the daunting terrain in which it is found, make this a rare Pogo indeed.

At the present time, P.anzensis is known definitively from only a few locations in Anza-Borrego Desert State Park (ABDP) in San Diego County, California USA.

Pogonomyrmex anzensis workers are red in color, and length is about 6.0mm (Taber 1998). They are easily distinguished from other Pogos in the area by their 6-toothed mandibles (as opposed to 7). Other distinctive features include the prominent, carinate rugae (ridges) adorning the occipital corners of the head, and a very visible ventral process on the postpetiole ('tooth-like' projection on the underside of the second part of the 'waist').

Nests of this ant are cryptic (very difficult to spot), especially among the jumbled, rock-strewn slopes where they are found. They consist of a single, small entrance hole sometimes adorned with a small apron of fine sand, or a tiny amount of almost invisible chaff (discarded plant material) (Snelling 2002). So far, these ants (and their nests) have only been found on west or southwest facing slopes; steep, and covered with large rocks (R.Snelling, G.Snelling, Schmidt and Cover 2009). This choice of habitat is unusual for Pogonomyrmex ants, and is the reason this ant eluded searchers for so many years.

In April 2011, we located and photographed live P.anzensis workers (and two nests) in the Pegleg Smith Monument area, on the border of ABDP and Borrego Springs, CA. Previously, a dead P.anzensis worker had been found in a spider web at this location (R.Snelling, G.Snelling, Schmidt and Cover 2009), so their presence here was suspected, (to our knowledge no live ants of this species had been seen here until our April 2011 visit). At this location we observed foraging workers transporting seeds of brittlebush (Encelia farinosa), and taking them into the nest. In addition to the Pegleg locality, we observed and imaged live workers at the Ocotillo Wells Vehicular Recreation Area, a locality they were known to inhabit (R.Snelling, G.Snelling, Schmidt and Cover 2009).

We noted (as have others) that the workers of this species are very docile - no aggressive or defensive behaviors were elicited when photographing these ants.

Special thanks to Gordon C. Snelling (armyants.org) for information and advice regarding P. anzensis.

[IMAGE ABOVE: P.anzensis worker cleaning her antennae in Ocotillo Wells V.R.A., California USA] [scroll down for additional notes/references]

References for entire page :

·Cole, A.C. 1968. Pogonomyrmex Harvester Ants: A Study of the Genus in North America. Knoxville, University of Tennessee Press
·Schmidt, J.O. & G.C. Snelling. 2009. Pogonomyrmex anzensis Cole: Does an Unusual Harvester Ant Species Have Unusual Venom? Journal of Hymenoptera Research, Vol. 18(2), 2009, pp. 322-325
·Snelling, G.C. 2002. The Quest for Pogonomyrmex anzensis Cole. Notes from Underground, 23 May, 2002
·Snelling, R.R., G.C. Snelling, J.O. Schmidt & S.P. Cover. 2009. The Sexual Castes of Pogonomyrmex anzensis Cole (Hymenoptera: Formicidae). Journal of Hymenoptera Research, Vol. 18(2), 2009, pp. 315-321
·Taber, S.W. 1998. The World of the Harvester Ants. College Station, TX, Texas A&M University Press