37Freshwater macroinvertebrates, and specifically Odonata, are considered among the most 38 endangered faunal groups. Their biomonitoring has been progressively supported by DNA-39 based tools whose performance and accuracy rely on validated reference datasets that, in some 40 cases, are lacking or do not cover important biogeographical centres of diversification. 41This study reports the results of a DNA barcoding campaign on Odonata, involving the 42 collection of 812 specimens (448 of which barcoded) from Italy and its main islands (328 43 localities), belonging to the 88 species (31 Zygoptera and 57 Anisoptera) inhabiting the country. 44 Additional BOLD and GenBank data from Holarctic samples of the same taxa expanded the 45 dataset to 1294 DNA barcodes. An integrative species delimitation analysis involving two 46 distance (OT and ABGD) and four tree-based (PTP, MPTP, GMYC, bGMYC) approaches 47 identified warnings of possible taxonomic relevance. Of the 88 investigated species, 85% could 48 be successfully identified by their DNA barcodes, with damselflies showing a percentage of 49 warnings (29%) higher than dragonflies (7%), contrasting with the other available DNA 50 barcoding studies on Odonata (showing up to 95% of identification success). The species 51causing warnings were grouped in three categories depending on if they showed low, high or 52 mixed genetic divergence patterns. Moreover, for the second class of warnings, the analysis of 53 haplotypes revealed unexpected structure at the Italian, Palearctic and Holarctic scale. Overall, 54 the DNA barcoding inventory assembled in this study will provide valuable insights into the 55 systematics and conservation of many odonate species with implications for future DNA and 56 eDNA monitoring-based studies. 57 58