Nanitic P.salinus worker.

Nanitic workers are smaller (dwarfish) workers often produced from a newly-mated queen's first brood. Nanitic workers can also result in times of near colony starvation [1].

A queen is said to be fully claustral (able to remain sealed in the nest, and to produce her first brood solely on her own bodily nutritional reserves), or semi claustral (production of her first brood produced using bodily reserves, augmented by active foraging for food outside of the nest). Very small nanitic workers are probably more likely to be produced by fully claustral queens, than by those semi claustral queens that forage as well. The literature indicates that P. salinus queens have been known to forage, at least on occasion [2].

In addition to being smaller, the nanitic workers of (P. salinus) we have observed in Oregon an Washington are bright orange-red in color - often strikingly different from the darker 'normal' workers from older colonies. We have also observed that they often hold the gaster (abdomen) tucked under the body, in a 'tail-between-the-legs' posture (not pictured here) [3]. [IMAGE: nanitic P. salinus worker foraging in central Washington] [scroll down for additional notes/references]

ADDITIONAL NOTES/REFERENCES:

[1]
·Hölldobler, B. & E.O. Wilson.1990. The Ants. Cambridge, MA, Belknap/Harvard Press

[2]
·Johnson, R.A. 2002. Semi-Claustral Colony Founding in the Seed-Harvester Ant Pogonomyrmex californicus: a Comparative Analysis of Colony Founding Strategies. Oecologica (2002) 132:60-67

[3]
This posture is also described as being used by 'patrollers' of Pogonomyrmex barbatus, as they lay down secretions from the Dufour's gland, as a means of initiating foraging along specific trails. We have not (yet) seen this in the P. salinus colonies we have observed. Aside from the nanitic workers of incipient colonies, we occasionally see a worker with the gaster tucked under the body, but this has always been observed later in the day, and did not appear to be related to the laying of chemical trails.

·Greene, M.J. & D.M. Gordon. 2007. How Patrollers Set Foraging Direction in Harvester Ants. The American Naturalist, Vol. 170, No. 6, December 2007