The species in this genus are seed-harvesting ants, whose nest mounds are often conspicuously decorated with pebbles. The workers are diurnal and have a potent sting.
Several of the taxa belong to difficult complexes, and species boundaries remain unclear. In neighboring Arizona a series of stabilized hybrid lineages has been documented in the P. barbatus-complex (Helms Cahan et al. 2002).
Species identification: keys in Cole (1966), Wheeler and Wheeler (1986g) and Mackay and Mackay (2002). Additional references: Davidson (1977a), De Vita (1979), Gordon (1999), Groark (2001), Helms Cahan et al. (2002), Hölldobler (1976a, 1976c), Johnson (2000a, 2001), Knudtson (1978), Kusnezov (1951e), Lei (2000), MacKay (1980, 1981, 1982), MacKay and MacKay (1989), O’Dowd and Hay (1980), Olsen (1934), Parker and Rissing (2002), Ryti and Case (1988), Schmidt (1998), Shattuck (1987), Snelling(1982a), Taber (1990, 1998), Taber et al. (1987, 1988), Wheeler (1902a, 1914e).
