Shape variation of Cydianerus latruncularius (Coleoptera, Curculionidae) across biomes and sexes

Cydianerus latruncularius (Perty, 1832) is a broad-nosed weevil (Entiminae) with South American distribution. In the past few years, some cases were observed where morphological modifications can occur on different populations of widely distributed species in various animal groups, including insects. Currently, geometric morphometrics is one of the most reliable and substantial ways to analyze shape variation among organisms. This technique is based on analysis of landmarks and their deviation on different individuals, identifying or not, conspicuous changes among them. It is a very useful tool to test shape variation among groups of organisms under different environmental pressures, whatever they might be. Knowing about the wide distribution and environmental diversity (Rainforests, Cerrado, Caatinga) occupied by C. latruncularius, the following research aims to discover if there are any shape patterns among sexes and individuals from different Brazilian ecosystems. Images of males and females’ pronotum, elytra and ventrite were landmarked in order to obtain morphological data which was then analyzed through MorphoJ software. Variations were found in all structures, which presented different results throughout the analysis. Pronotum proved to be a determinant structure to separate Amazonian populations from the others. The elytra formed groups only among males from Cerrado and Rainforests, while all females were overlapping. Also, the ventrites proved to be the best structures to describe sexual dimorphism. Geometric morphometrics of C. latruncularius allowed us to verify that the shape of different body parts varies in an independent way among them and are possibly influenced by the environment.