Abstract

Sexual dimorphism may be expressed through absolute dimensions, relative proportions, and shape, yet these components have not been jointly evaluated in Dorcadion parilis, a Turkish endemic member of a flightless and taxonomically challenging genus. We examined 85 specimens (35 females and 50 males) using traditional and geometric morphometrics, sex-controlled allometric models, and two-block partial least squares analysis. Males had longer pronota, whereas females had wider pronota and longer and wider elytra. After Mosimann adjustment, the clearest differences were relatively longer pronota in males and broader elytra in females, while elytral length no longer differed. Pronotal and elytral shapes also differed between sexes, with stronger and more widespread differentiation in the pronotum and more localized elytral differences. Initial size–shape associations were not retained as independent effects after accounting for sex, and there was no evidence of sex-specific allometric slopes. Significant residual covariation between pronotal and elytral shapes persisted after adjustment for sex and structure-specific size. These findings show that sexual dimorphism in D. parilis is multidimensional and structure-specific rather than a simple consequence of centroid size and highlight the value of geometric morphometrics for detecting sex-related shape variation not fully captured by linear measurements and proportions.

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