Pumpkinseed (Lepomis gibbosus) is an exotic fish species widely distributed in Europe and it has expanded its distribution area in Turkey since its first report in 1982. It is well known that invasive species like L. gibbosus adapt to introduced habitats relatively well. In order to evaluate morphological variation within this invasive species, sampling was carried out in June 2012 and May 2013 in the Aegean and Thrace regions, respectively. Body-form variability in sampled populations of L. gibbosus was investigated using landmark-based geometric morphometrics. L. gibbosus showed significant geographic- and habitat-based differences with and without allometric standardization. However, outcomes of these results differed significantly. Differences between locality-based Procrustes distances were found to support habitat-based differentiation. These results suggest that, depending on the hypothesis of the morphometric study, it might be important to implement allometric regression and standardization. Additionally, the range extension of L. gibbosus needs to be monitored carefully. It had previously been reported only from the Thrace and Mugla regions. However, according to our data, it has been sampled from two new basins, Susurluk and Sakarya.