Measurements (in mm; mean ± SE) for the three female castes of Pogonomyrmex laticeps.

*HW – maximum width of the head, positioned in full face view, at a level above the upper eye margin;HL - maximum length of the head, full face view, from the midpoint of the anterior clypeal margin to the midpoint of the occipital margin; MOD – maximum diameter of the eye as measured with the head in full lateral aspect; SL – maximum length of the scape, including the basal condyle; OD – maximum diameter of the anterior ocellus; PW1–3 – maximum width of pronotum, petiole, and post-petiole, respectively, as seen from above, at right angles to the longitudinal axis of the body; ML - diagonal length of the thorax in profile from the anterior pronotal margin to the posterior base of the metapleural lobe; HFL – length of the hind femur, measured along the dorsal margin from the articulation with the trochanter to the most distal tip of the femur; TW – maximum width of first gastral tergite, as seen from above, perpendicular to the longitudinal axis.+ = For external morphological characters: n = 40 workers (15 at Chilecito [CH], 25 at Punta Balasto [PB]), n = 25 ergatoid queens (CH), n = 30 brachypterous queens (PB); for internal characters: n = 8 workers (2 at CH, 6 at PB), n = 5 ergatoid queens, n = 3 brachypterous queens (see text for details). Significant differences among castes are given by the letters a-d: a > b > c > d. Groupings are based on univariate F tests within a MANOVA followed by a Duncan’s multiple range test for continuous variables or a Kruskal-Wallis test for discrete variables (see text). Characters in bold font were used in the discriminant analysis.