Quantitative image analysis applied to revise the taxonomy of the Palearctic <i>Earophila badiata</i> species group (Lepidoptera: Geometridae: Larentiinae)

The geometrid moth <i>Earophila badiata</i> (Denis & Schiffermüller, 1775), which occurs widely in the Palearctic realm, has rapidly filled a large gap in its range across southern Finland during the past two decades, prompting a re-evaluation of its taxonomy. Using an integrative taxonomic approach including a quantitative wing image analysis combined with genitalia morphology and mitochondrial DNA barcoding (mtCOI) analyses, we reassessed the status of the described taxa within the <i>E. badiata</i> species group. Quantitative analysis of forewing colours revealed strong sexual dimorphism and significant effects of specimen wear and age on colouration, but no consistent morphological differences between the nominotypical subspecies <i>E. badiata badiata</i> and taxon <i>E. badiata fennokarelica</i> (Kaisila, 1945). Comparative genitalia morphology, including micro-CT imaging, showed no diagnostic differences among closely related <i>E. badiata</i>, <i>E. kolomietsi</i> Vasilenko, 2003, and <i>E. pseudobadiata</i> Vasilenko, 2007, supporting the synonymy of these taxa. Molecular phylogeny and haplotype analysis confirmed monophyly among Eurasian samples with low genetic divergence (<0.63%), but implying a distinct lineage for North African <i>E. badiata tellensis</i> (Herbulot, 1957). Based on these findings, we propose synonymizing <i>E. kolomietsi</i> and <i>E. pseudobadiata</i> with <i>E. badiata</i> syn. n. and classify the <i>E. badiata</i> taxon <i>fennokarelica</i> as a morphological form of <i>E. badiata</i> below the subspecific rank. Our results challenge the current subspecies delineation and support a revision of taxonomic boundaries within this group, highlighting the value of integrative taxonomy for resolving complex relationships among closely related species.