Fanniidae (Diptera) of forensic importance, with an identification key for third instar larvae of European species

Fanniidae are a dipteran family of growing importance in medico-legal entomology. Several fanniid species are well known to colonise decomposing human remains and animal carcasses, making them potentially valuable indicators for estimating the post-mortem interval (PMI) and reconstructing circumstances of death. In recent years, however, surveys of carrion-associated arthropod assemblages have revealed a much broader diversity of Fanniidae than previously recognised. Despite this, the full range of species of fanniids breeding in cadavers remains insufficiently studied, and identification tools for immature stages are still incomplete. This study provides a key enabling identification of third instar larvae of European species confirmed to colonise human cadavers and the carrion of other animals and a worldwide catalogue of carrion-visiting Fanniidae. For taxa in which larval morphology alone does not allow unambiguous identification, we discuss an integrative approach to taxonomy combining morphological examination with DNA barcoding and species distribution data. The present study fills a major gap in the taxonomy of immature stages of forensically important Diptera and provides a tool allowing for broader application of fanniids in medico-legal investigations.