The Central–marginal hypothesis predicts that populations occurring at the periphery of a species’ geographic distribution experience more adverse environmental conditions, resulting in reduced population density, lower fitness, and potential morphological changes. In insects, morphological traits are closely associated with ecological performance and resource acquisition, making them useful indicators of how populations respond to environmental gradients. Here, we investigated whether populations of the ant Dinoponera quadriceps differ in abundance and morphofunctional traits between the center and edge of the species’ geographic distribution along the Espinhaço Mountain Range, Brazil. Ants were sampled using pitfall traps in two sites approximately 610 km apart. Generalized Linear Mixed Models were used to evaluate differences in abundance and trait variation between sites, and a Principal Component Analysis summarized multivariate body size variation. The abundance of D. quadriceps was significantly higher in central populations and was positively correlated with the richness of other ant species. Individuals from the marginal population exhibited significantly smaller overall body size. Additionally, trait-specific differences emerged, with marginal individuals displaying larger cephalic index, longer femora, and larger eyes. These findings suggest that peripheral environments impose energetic constraints that reduce body size while favoring morphological adjustments that enhance locomotor and sensory efficiency, highlighting the importance of intraspecific functional variation in understanding species responses at geographic range limits.