Shape variation in Sericoidini (Coleoptera: Melolonthidae: Sericoidinae) with emphasis on Blepharotoma Blanchard, 1850 using geometric morphometrics

Abstract

Sericoidini is a tribe of Melolonthinae (Sericoidinae) with five genera (Apterodemidea, Blepharotoma, Manonychus, Ovomanonychus and Sericoides) distributed throughout the neotropical region. All these genera, with the exception of Ovomanonychus, are in need of taxonomic reassessment. Blepharotoma Blanchard is the second largest genus of the tribe, and due to undergoing several new descriptions and transferences over the years has its intern limits become uncertain. Geometric morphometrics has been helping identify patterns among groups of organisms with uncertain limits. This method enables the identification of variations in shape among specimens through comparisons of landmarks coordinates. The aim of the present study was to test the existence of significant morphometric variation among the genera of Sericoidini and species of Blepharotoma that could enable identifying taxa. We analyzed the clypeus, pronotum and elytra of species of each genus of Sericoidini and 18 valid species of Blepharotoma. A photographic matrix was created with images of the structures and a set of landmarks was plotted in each image. Procrustes superimposition was performed, and the data were analyzed using principal component analysis (PCA), Procrustes ANOVA and canonical variate analysis (CVA). Groups for CVA were classified by genera, species and collection site. The results showed that genera of Sericoidini have a shape pattern. In contrast, species of Blepharotoma do not have any specific pattern, except for the population from Buenos Aires (unidentified species). In conclusion, geometric morphometrics seems to be a good support tool for the taxonomic classification of genera of Sericoidini.