Identification of Cryptic Beetle Species in the Cyclocephala Complex Using Reflectance Spectroscopy.

Abstract

Several methods are available for identifying insect species, primarily based on morphological characteristics, molecular taxonomy, and geometric morphometry. However, integrative taxonomy is emerging as a robust approach, especially for closely related or taxonomically challenging species. In this study, reflectance spectroscopy in the visible and near-infrared ranges was employed to identify three beetle species within the Cyclocephala complex. A multivariate analysis of the spectral data enabled the development of a standardized methodology for identifying species with complex taxonomy by using spectral measurements from the beetles' elytra. Eight specific wavelengths-400 nm, 430, 440, 480 nm, 640 nm, 680 nm, 710 nm, and 1000 nm-were identified as promising for use in indices and models applicable to Cyclocephala taxonomy. Linear discriminant models applied to the spectral reflectance data successfully separated species with classification accuracy up to 84%. These findings highlight the potential of reflectance spectroscopy within the 400-1000 nm range as part of a comprehensive methodology for discriminating insect species complexes.