Data from: Starting a DNA barcode reference library for shallow water polychaetes from the southern European Atlantic coast

Annelid polychaetes have been seldom the focus of dedicated DNA barcoding studies, despite their ecological relevance and often dominance, particularly in soft-bottom estuarine and coastal marine ecosystems. Here, we report the first assessment of the performance of DNA barcodes in the discrimination of shallow water polychaete species from the southern European Atlantic coast, focusing on specimens collected in estuaries and coastal ecosystems of Portugal. We analysed cytochrome oxidase I DNA barcodes (COI-5P) from 164 specimens, which were assigned to 51 morphospecies. To our data set from Portugal, we added available published sequences selected from the same species, genus or family, to inspect for taxonomic congruence among studies and collection location. The final data set comprised 290 specimens and 79 morphospecies, which generated 99 Barcode Index Numbers (BINs) within Barcode of Life Data Systems (BOLD). Among these, 22 BINs were singletons, 47 other BINs were concordant, confirming the initial identification based on morphological characters, and 30 were discordant, most of which consisted on multiple BINs found for the same morphospecies. Some of the most prominent cases in the latter category include Hediste diversicolor (O.F. Müller, 1776) (7), Eulalia viridis (Linnaeus, 1767) (2) and Owenia fusiformis (delle Chiaje, 1844) (5), all of them reported from Portugal and frequently used in ecological studies as environmental quality indicators. Our results for these species showed discordance between molecular lineages and morphospecies, or added additional relatively divergent lineages. The potential inaccuracies in environmental assessments, where underpinning polychaete species diversity is poorly resolved or clarified, demand additional and extensive investigation of the DNA barcode diversity in this group, in parallel with alpha taxonomy efforts.多毛类环节动物（Annelid polychaetes）虽具有重要生态意义，且常在软底质河口与近岸海洋生态系统中占据优势类群地位，但相关专属DNA条码（DNA barcoding）研究却鲜有开展。本研究首次评估了DNA条码对欧洲南部大西洋沿岸浅海多毛类物种的区分效能，研究对象为采自葡萄牙河口与近岸生态系统的标本。我们对164份标本的细胞色素氧化酶I DNA条码（COI-5P）进行了分析，这些标本隶属于51个形态种。我们将葡萄牙数据集与从同一物种、属或类群中获取的已发表序列相结合，以检验不同研究及采样地点间的分类学一致性。最终数据集共包含290份标本与79个形态种，在生命条码数据系统（Barcode of Life Data Systems, BOLD）中共生成99个条码索引编号（Barcode Index Numbers, BINs）。其中22个BIN为单例序列，47个BIN与形态鉴定结果一致，证实了基于形态特征的初始鉴定结果，剩余30个BIN则存在分类学不一致性，其中多数表现为同一形态种对应多个BIN。此类不一致性的典型案例包括：异足索沙蚕（Hediste diversicolor, O.F. Müller, 1776）（7个BIN）、翠绿矶沙蚕（Eulalia viridis, Linnaeus, 1767）（2个BIN）以及帚毛虫（Owenia fusiformis, delle Chiaje, 1844）（5个BIN），上述物种均在葡萄牙有记录，且常作为环境质量指示物种被应用于生态学研究。本研究针对这些物种的分析结果显示，分子谱系与形态种之间存在不一致性，或额外引入了相对分化程度较高的谱系。在以多毛类物种多样性为基础的环境评估中，若物种多样性界定模糊不清，则可能导致评估结果存在潜在偏差，这一问题亟需针对该类群开展更为广泛深入的DNA条码多样性研究，同时配合经典阿尔法分类学（alpha taxonomy）工作推进。