During last decades, taxonomy was strongly improved by integrating molecular techniques with classical morphological methods, leading to the discovery of cryptic species. On the other hand, molecular datasets by itself are ineffective without basic taxonomic studies in several kind of research because ecological and biological role of a given species cannot be obtained without a name. DNA barcoding libraries are largely utilised as identification tools by non-specialists overcoming the taxonomic impediment, but they fail when basic taxonomic studies are poor and faunistic inventories are lacking. South European microlepidoptera are scarcely studied except few families such as Depressariidae. We tested the effectiveness of the DNA barcoding library of this family to identify 174 specimens collected in South Italy, where faunistic studies are very scarce. All specimens were successfully barcoded and the 95% of them were assigned to 47 species of which 43 correspond to a Barcode Index Number (BIN). Four more species shared a BIN but were still clearly separated on different clusters at a within-BIN resolution. Only seven specimens belonging to four BINs remain unnamed and ad hoc studies are needed to clarify their status. The regional fauna was enriched by 37 species three of which new for Italian mainland, and 21 for peninsular Italy demonstrating the usefulness of the DNA barcoding library in assessing local diversity overcoming the taxonomic impediment. Improving taxonomic studies is crucial to utilise molecular datasets to depict ongoing macroecological dynamics pointing out species richness trends and changes in species assemblages.