Phylogeography of the micro-endemic Pedicia staryi group (Insecta: Diptera): evidence of relict biodiversity in the Carpathians

The Carpathian region is recognized as one of the most important hotspots for aquatic biodiversity in Europe. In the present study, 658-bp long nucleotide sequences from the mitochondrial cytochrome c oxidase subunit I (mtCOI) gene were used to study the phylogeographical patterns of the Carpathian endemic dipteran species belonging to the Pedicia staryi group. Molecular data support the taxon status of the allopatric sibling pairs of the morphologically highly similar Pedicia apusenica, Pedicia staryi, and Pedicia lobifera. This pattern is most likely the result of long-term isolation in so-called cumulative microrefugia in the Carpathians, caused by aridification and forest fragmentation in the Miocene-Pliocene period, in combination with the specific habitat requirements of these species (i.e. the wet and humid environments of forested headwater springs). Furthermore, molecular data reveal an important cryptic diversity in the case of the most wide-spread Carpathian P.staryi, as represented by highly divergent, allopatric populations from distant mountainous ranges, already recognized as important centres of endemism for aquatic insects. In addition, an unexpectedly high genetic diversity was identified in populations from the Rodnei Mountains, where the northern and southern slopes harbour highly divergent genetic lineages. This highlights the importance of this mountain range in the preservation of autochthonous diversity in the Carpathians. The present study provides important new evidence regarding the persistence of relic species in spring habitats in the Carpathians, with ancient divergence events that predate Quaternary glaciations and confirm their continuous presence during the Last Glacial Maximum in multiple isolated refugia, leading finally to a high genetic complexity in these particular aquatic ecosystems.