New taxonomic data on mud-loving beetles are provided based on morphological characters and DNA barcoding. Heterocerus heydeni Kuwert, 1890 was previously considered a junior synonym of H. flexuosus Stephens, 1828, but we support the validity of the species and restore the name. H. heydeni is redescribed, based on material from Central Asia and European part of Russia. Specimens of H. hauseri Kuwert, 1893 were also studied, suggesting it as a possible junior synonym of H. heydeni. We provide new DNA barcodes for H. flexuosus and Augyles cf. flavidus and comment on Heterocerus barcode data published in Barcode Of Life Data Systems (BOLD).
Keywords: Coleoptera, Byrrhoidea, Heteroceridae, synonymy, sibling species, DNA barcoding, Central Asia, European Russia, BOLD.