Data from: DNA barcoding and minibarcoding as a powerful tool for feather mite studies

Feather mites (Astigmata: Analgoidea and Pterolichoidea) are among the most abundant and commonly occurring bird ectosymbionts. Basic questions on the ecology and evolution of feather mites remain unanswered because feather mite species identification is often only possible for adult males, and it is laborious even for specialized taxonomists, thus precluding large-scale identifications. Here, we tested DNA barcoding as a useful molecular tool to identify feather mites from passerine birds. Three hundred and sixty-one specimens of 72 species of feather mites from 68 species of European passerine birds from Russia and Spain were barcoded. The accuracy of barcoding and minibarcoding was tested. Moreover, threshold choice (a controversial issue in barcoding studies) was also explored in a new way, by calculating through simulations the effect of sampling effort (in species number and species composition) on threshold calculations. We found one 200-bp minibarcode region that showed the same accuracy as the full-length barcode (602 bp) and was surrounded by conserved regions potentially useful for group-specific degenerate primers. Species identification accuracy was perfect (100%) but decreased when singletons or species of the Proctophyllodes pinnatus group were included. In fact, barcoding confirmed previous taxonomic issues within the P. pinnatus group. Following an integrative taxonomy approach, we compared our barcode study with previous taxonomic knowledge on feather mites, discovering three new putative cryptic species and validating three previous morphologically different (but still undescribed) new species.羽螨(Feather mites)隶属于无气门亚目(Astigmata)的食甜螨总科(Analgoidea)与羽螨总科(Pterolichoidea)，是鸟类体表共生生物中丰度最高、分布最广的类群之一。关于羽螨的生态学与演化的基础问题迄今仍未得到解答，其核心阻碍在于羽螨的物种鉴定通常仅能依托雄性成虫完成，即便对于专业分类学家而言也极为耗时费力，极大限制了大规模物种鉴定工作的开展。本研究将DNA条形码(DNA barcoding)作为实用分子工具，用于鉴定雀形目鸟类(passerine birds)体表的羽螨。研究共对采自俄罗斯与西班牙的68种欧洲雀形目鸟类体表的72种羽螨的361个标本开展了条形码测序。本研究测试了全长度条形码与迷你条形码(minibarcoding)的鉴定准确率，同时以全新思路探讨了条形码研究中颇具争议的阈值选择问题：通过模拟计算采样量（涵盖物种数量与物种组成）对阈值计算的影响。研究发现一段长度为200碱基对(bp)的迷你条形码区域，其鉴定准确率与全长602碱基对的条形码完全一致，且该区域两侧存在保守序列，有望用于设计类群特异性简并引物(degenerate primers)。整体物种鉴定准确率可达100%，但当纳入单例标本(singletons)或pinnatus羽盾螨(Proctophyllodes pinnatus)类群的物种时，准确率会出现下降。事实上，条形码测序结果证实了pinnatus羽盾螨类群中此前存在的分类学争议。本研究采用综合分类学(integrative taxonomy)方法，将本研究的条形码数据与此前的羽螨分类学认知进行比对，最终发现了3个潜在的隐存种(cryptic species)新种，并验证了3个此前已在形态上存在差异但尚未被正式描述的新物种。