Geometric Morphology Reveals Species Differences and Sexual Dimorphism in Two Species of Premnotrypes Pierce (Coleoptera: Curculionidae)

The beetles of the genus Premnotrypes Pierce (Coleoptera: Curculionidae) are major pests of potato crops in high Andean agroecosystems, where two or more species can coexist in the same area. Identification of Premnotrypes species and sexes can be difficult because diagnostic characters are mostly associated with genitalia, and they have similar body sizes. Therefore, reliable methods for accurate species identification are essential. In this study, we characterized and analyzed the shape and size of two Premnotrypes species, Premnotrypes fractirostris Marshall and Premnotrypes latithorax Pierce, using a geometric morphometric approach to identify potential morphological differences related to species identity and intraspecific sexual dimorphism. We analyzed the shape and size of the dorsal surface of the pronotum and elytra in adults of P. fractirostris and P. latithorax. Both interspecific and intraspecific variation were detected. Premnotrypes fractirostris and P. latithorax differed significantly in size and shape of both the pronotum and elytra. Additionally, although both species displayed sexual dimorphism in pronotal and elytral shape, only P. fractirostris exhibited sexual dimorphism in size for these structures. Our results demonstrate that morphometric analyses of the pronotum and elytra (shape and size) provide an effective tool for species and sex discrimination within the genus Premnotrypes.