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.尽管多毛类环节动物（Annelid polychaetes）具备关键生态价值，且在软底质河口与近岸海洋生态系统中常占据优势类群地位，但针对该类群的专门DNA条形码（DNA barcoding）研究却相对匮乏。本研究首次针对欧洲南部大西洋沿岸的浅海多毛类物种，评估了DNA条形码的物种区分效能，研究样本采集自葡萄牙的河口与近岸生态系统。我们对164份标本的细胞色素氧化酶I DNA条形码（COI-5P）进行了分析，这些标本被划归为51个形态种（morphospecies）。我们将葡萄牙数据集与来自同一物种、属或科的已公开序列进行整合，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，在生命条形码数据系统（BOLD）中生成了99个条形码索引号（BINs）。其中22个BIN为单例BIN，47个BIN与基于形态特征的初始分类鉴定结果一致，验证了该鉴定的可靠性；剩余30个BIN则存在分类不一致性，其中多数表现为同一形态种对应多个不同BIN的情况。此类不一致性中最典型的案例包括：异索沙蚕（Hediste diversicolor, O.F. Müller, 1776）（对应7个BIN）、翠绿艾利沙蚕（Eulalia viridis, Linnaeus, 1767）（对应2个BIN）以及纺锤欧文虫（Owenia fusiformis, delle Chiaje, 1844）（对应5个BIN）。上述物种均在葡萄牙有分布记录，且常作为环境质量指示物种应用于生态学研究。针对这些物种的分析结果显示，其分子谱系与形态种之间存在不一致性，或新增了相对分化程度较高的谱系分支。在以多毛类物种多样性为核心支撑的环境评估中，若该类群的多样性尚未得到充分解析或明确，则可能出现评估结果不准确的问题。对此，亟需针对该类群开展更为广泛的DNA条形码多样性研究，并同步推进阿尔法分类学（alpha taxonomy）相关工作。