Pogonomyrmex laticeps

Distribution based on Regional Taxon Lists
Neotropical Region: Argentina.

Castes
This species has dimorphic queens: ergatoid (permanently wingless) and brachypterous (short, non-functional wings). Surveys by Peeters et al. (2012) in western Argentina indicated that colonies near Chilecito, La Rioja Province, produced only ergatoid queens, while those near Punta Balasto, Catamarca Province (263 km away), produced only brachypterous queens. Brachypterous queens were significantly larger than ergatoid queens for 10 of 11 external characters, but both phenotypes had comparable reproductive potential, i.e., a spermatheca and a similar number of ovarioles. Using normal winged queens of the closely related P. uruguayensis for comparison, we determined that both queen phenotypes in P. laticeps had a full set of dorsal thoracic sclerites, albeit each sclerite was much reduced, whereas workers have a thorax without distinct dorsal sclerites. Sclerites were fused and immobile in ergatoid queens, while they were separable and fully articulated in brachypterous queens. Both phenotypes lacked the big indirect flight muscles, but brachypterous queens retained the tiny direct flight muscles. Overall, this dimorphism across populations indicates that there are alternative solutions to selective pressures against flying queens. We lack field data about colony founding strategy (independent or dependent) for either queen phenotype, but colonies at both sites produced numerous gynes, and we infer that all foundresses initiate colonies independently and are obligate foragers.

Nomenclature

 *  laticeps. Pogonomyrmex laticeps Santschi, 1922b: 350 (w.) ARGENTINA. Kusnezov, 1951a: 274 (ergatoid q.).

Type Material
Syntypes: 2 workers [MACN], ARGENTINA, Catamarca: Masao, #1376 (Weiser leg., March 1921). MACN worker [CASENT0217255] designated LECTOTYPE by Johnson, 2015: 80.