Semenchenko A.A., Teslenko V.A.
Far Eastern Entomologist 2026; (560): 17-32
In this study, we successfully generated mitochondrial cytochrome c oxidase subunit I (COI) DNA barcodes for 10 stonefly specimens belonging to three Eastern Palearctic species of the genus Alloperla Banks, 1906: A. mediata (Navás, 1925), A. rostellata (Klapálek, 1923), and A. teleckojensis Šámal, 1939. Based on both morphological features and molecular evidence, Alloperla ishikariana Kohno, 1953 from Japan was found to be conspecific with the widespread A. mediata and is hereby formally downgraded to its junior synonym. A genus-wide phylogenetic reconstruction and species delimitation revealed three distinct types of incongruence between current public sequence repositories and morphological taxonomy: 1) several distinct morphospecies shared single mOTU, 2) a single morphospecies splitting into multiple distant non-monophyletic molecular operational taxonomic units (mOTUs), and 3) strictly monophyletic lineages of a single species being artificially fragmented into different mOTUs due to the over-sensitivity of the BOLD and ASAP frameworks. Pairwise divergence histograms combined with a blind kernel density estimation analysis via the spider library conclusively demonstrated that the macro-evolutionary barcoding gap occurs at exactly 6.1%. Implementing this empirically derived threshold successfully corrected algorithmic over-splitting and validated the conspecificity of deeply divergent allopatric populations within Alloperla chloris Frison, 1934, A. petasata Surdick, 2004, A. teleckojensis, and A. mediata.
