Data from: A comprehensive DNA barcode database for Central European beetles with a focus on Germany: adding more than 3,500 identified species to BOLD

Beetles are the most diverse group of animals and are crucial for ecosystem functioning. In many countries, they are well established for environmental impact assessment, but even in the well-studied Central European fauna, species identification can be very difficult. A comprehensive and taxonomically well-curated DNA barcode library could remedy this deficit and could also link hundreds of years of traditional knowledge with next generation sequencing technology. However, such a beetle library is missing to date. This study provides the globally largest DNA barcode reference library for Coleoptera for 15 948 individuals belonging to 3514 well-identified species (53% of the German fauna) with representatives from 97 of 103 families (94%). This study is the first comprehensive regional test of the efficiency of DNA barcoding for beetles with a focus on Germany. Sequences ≥500 bp were recovered from 63% of the specimens analysed (15 948 of 25 294) with short sequences from another 997 specimens. Whereas most specimens (92.2%) could be unambiguously assigned to a single known species by sequence diversity at CO1, 1089 specimens (6.8%) were assigned to more than one Barcode Index Number (BIN), creating 395 BINs which need further study to ascertain if they represent cryptic species, mitochondrial introgression, or simply regional variation in widespread species. We found 409 specimens (2.6%) that shared a BIN assignment with another species, most involving a pair of closely allied species as 43 BINs were involved. Most of these taxa were separated by barcodes although sequence divergences were low. Only 155 specimens (0.97%) show identical or overlapping clusters.甲虫（鞘翅目，Coleoptera）是物种多样性最为丰富的动物类群，对生态系统功能维持具有关键作用。在诸多国家，甲虫已被广泛应用于环境影响评价工作，但即便在研究较为充分的中欧动物区系中，物种鉴定仍极具挑战性。兼具全面性与分类学严谨性的DNA条形码（DNA barcode）参考库，不仅可弥补这一短板，还能将数百年来积累的传统分类学知识与下一代测序技术有机结合。然而迄今为止，这类甲虫DNA条形码参考库仍付诸阙如。 本研究构建了目前全球规模最大的鞘翅目DNA条形码参考库，涵盖15948个标本，隶属于3514个经精准鉴定的物种（占德国已知鞘翅目物种的53%），样本覆盖103个科中的97个（覆盖度达94%）。本研究也是首个以德国为研究区域的鞘翅目DNA条形码鉴定效率的综合性区域性测试。在本次分析的25294个标本中，63%（15948个）成功获得了长度≥500bp的有效序列，另有997个标本获得了短序列片段。尽管92.2%的标本可通过CO1基因的序列多样性被精准匹配至单一已知物种，但仍有1089个标本（占比6.8%）被划分至多个条形码索引号（Barcode Index Number, BIN），共计产生395个BIN，需进一步研究以明确其究竟代表隐存物种、线粒体基因渐渗，还是广布物种的区域性种群差异。另有409个标本（占比2.6%）与其他物种共享同一BIN，其中多数涉及一对近缘物种，共涉及43个BIN。尽管序列分歧度较低，但多数此类类群仍可通过条形码加以区分。仅有155个标本（占比0.97%）呈现序列簇完全一致或重叠的情况。