Paper available here.

Abstract: Four species complexes have been recognized for >20 yr; one is monotypic, and the compositions of the others have changed because of new descriptions and synonymy. An early prediction concerning the proper placement of one species is confirmed, and with this proviso, the three modified complexes are shown to be monophyletic. Two undescribed species are placed, resolutions of problematic relationships are offered, a new species complex is defined, range extensions are recorded, and a scanning electron micrographic study of North American Pogonomyrmex is concluded.