First Taxonomically Curated DNA Barcode Reference Library for Polish Myriapods Fills an Important Knowledge Gap for Soil Invertebrates in Central Europe, Part I: Millipedes (Myriapoda: Diplopoda).

DNA barcoding is a highly effective tool for species identification, complementing taxonomic and phylogenetic studies while also playing a key role in biomonitoring and uncovering cryptic diversity. Techniques such as DNA barcoding, metabarcoding and environmental DNA (eDNA) analysis are widely applied in biodiversity conservation, tracking invasive species and studying trophic interactions. To carry out this type of research effectively, a robust DNA barcode library is essential, built upon high-quality genetic sequences and accurate taxonomic identification. Here, we present the results of a large-scale DNA barcoding study of Polish diplopod species (Myriapoda: Diplopoda), providing an up-to-date checklist of species recorded in Poland and a reference DNA barcode library. We deliver data on 981 individuals identified to species level, of which 468 have COI sequence data. 58 out of 93 species recorded for Poland were successfully barcoded, representing 62% of the national fauna. Additionally, we explore future research directions, potential cryptic diversity and shifts in the national fauna, including newly recorded species for Poland-Melogona broelemanni (Verhoeff, 1897). Our findings highlight the significance of ongoing monitoring and molecular methods in tracking biodiversity changes.