The intraspecific variability of Colias croceus (Geoffroy, 1785) and C. erate (Esper, 1805) (Lepidoptera, Pieridae) from the perspective of comparative morphology

The sibling species Colias croceus and Colias erate show significant intraspecific variability, presumably resulting from frequent hybridization. For this reason, some specimens are not clearly identifiable. The yellow forms of males and the white forms of females are particularly problematic in terms of their identification. In this study, we investigated the reliability of external features for effective identification of this species pair using geometric morphometrics. The study specimens were tentatively identified to the species level based on genital characteristics and several genetic markers. Geometric morphometric analyses were focused on the variability of wings and male genital valvae of Slovak butterfly populations. The morphometric analysis of valvae enabled identification of most of the specimens, whereas based on the putatively diagnostic features of forewings and hindwings, several butterflies were incorrectly assigned to a species. Contrary to earlier observations, we observed that androconial scales are also present in some forms of C. erate.