An Analysis of Geographic Variation in the Pogonomyrmex Occidentalis Complex (Hymenoptera: Formicidae)

While examining samples of Pogonomyrmex from southeastern Oregon, I encountered difficulty in segragating the two species reported as occurring in the area, P. owyheei Cole and P. salinus Olsen (Cole, 1968). Analysis of material from Oregon, Nevada and Utah suggested that the taxonomy of these two forms needed reevaluation. Smith (1953) considered them a single species, but this view was subsequently rejected by Cole (1968). Cole (1963, 1968) described the occidentalis complex as composed of P. owyheei and salinus, together with P. anzensis Cole, brevispinosus Cole, occidentalis (Cresson), subdentatus Mayr and subnitidus Emery. MacKay (1980) described P. montanus from southern California, bringing the complex to a total of 8 species. Within the occidentalis complex, the species P. owyheeL salinus, occidentalis, subdentatus and montanus form a distinct, plausibly monophyletic group, united by the cephalic sculpturing, configuration of the antennal scape base, and thoracic sculpturing. This group is referred to here as the occidentalis subcomplex. Because they do not possess this combination of characters, and because monophyly of the occidentalis complex as a whole is uncertain, P. anzensis, brevispinosus and subnitidus were excluded from this group and the present study.