Molecular data confirm Monolepta hieroglyphica (Motschulsky, 1858) and M. quadriguttata (Motschulsky, 1860) being synonyms of M. signata (Oliver, 1808)

Monolepta hieroglyphica (Motschulsky, 1858) has been recently revised as the synonym of M. signata (Oliver, 1808) based on morphological characteristics. M. quadriguttata (Motschulsky, 1860) was synonymized with M. signata over 100 years ago. However, this synonymy has not be confirmed by molecular data. This widely distributed and abundant species shows a high variability in coloration patterns that caused numbers of synonyms. We selected color forms typical for the three nominal taxa for phylogenetic analysis. The phylogenetic, haplotype and genetic differentiation analysis of M. hieroglyphica, M. quadriguttata and M. signata were constructed to determine the relationships between them, and we also found mating behavior between them. They were intermixed together on phylogenetic trees, and M. hieroglyphica and M. quadriguttata had shared haplotype. There was no significant difference among them for genetic distance, and the synonymy of the three names based on external and genital characters can be confirmed by molecular data.