Validation of Heterocerus heydeni Kuwert, 1890 based on morphology and DNA barcoding, with notes on the problems of classification of the Heteroceridae (Coleoptera).

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).

Stenelmis koreana Satô, 1978 (Coleoptera: Elmidae): confirmed as a wide-spread species by DNA-sequencing.

Stenelmis koreana Satô, 1978 (Coleoptera: Elmidae) is here recorded for the first time from Kyrgyzstan and Western Siberia. It was hitherto thought to be confined to Korea and the Russian Far East. The identification of a specimen from Kyrgyzstan was confirmed by DNA-sequencing after comparison with two sequences of S. koreana from Korea. The COI haplotype of the Kyrgyzstan specimen has very low sequence divergence (0.53 % or 0.0053 uncorrected p-distance) with respect to the sequences of the Korean specimens, which is within the standard intraspecific sequence divergence for COI in beetles.