Mites (Arachnida: Acariformes, Parasitiformes) are the most abundant and species-rich group of arthropods in soil, but are also diverse in freshwater habitats, on plants, and as symbionts of larger animals. However, assessment of their diversity has been impeded by their small size and often cryptic morphology. As a consequence, published estimates of their species richness span more than two orders of magnitude (0.4-114 million). In this study we employ DNA barcoding and the Barcode Index Number (BIN) system to investigate mite diversity at over 1,800 sites across Canada, primarily from soil and litter habitats with smaller contributions from freshwater, plants, and animal hosts. Barcodes from 73,394 specimens revealed 7,077 BINs with representatives from all four orders (Ixodida, Mesostigmata, Sarcoptiformes, Trombidiformes) and 60% (186) of the known families. The BIN total is 2.4 times the number of species previously recorded from Canada (2,999), reflecting the unexpectedly high richness of several families. Richness projections suggest that more than 28,000 BINs occur at the sampled locations, indicating that the Canadian mite fauna almost certainly includes more than 30,000 species-a total similar to that for the most diverse insect order in Canada, Diptera. This unexpected diversity was partitioned into highly dissimilar, spatially-structured assemblages that likely reflect dispersal limitation and environmental heterogeneity. Further sampling of a greater diversity of habitats will refine understanding of mite diversity in Canada, but similar analyses in other geographic regions will be essential to ascertain their diversity at a global scale.

中文翻译：

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DNA条码暴露了加拿大螨类中意想不到的多样性。

螨虫（蛛形纲：蜘蛛纲，寄生纲）是土壤中节肢动物中种类最多，种类最丰富的一组，但在淡水生境，植物和大型动物的共生体中也多种多样。但是，由于它们的体积小且常常是隐秘的形态，因此妨碍了对其多样性的评估。结果，已发表的关于其物种丰富度的估计跨越了两个数量级（0.4-1.14亿）。在这项研究中，我们采用DNA条形码和条形码指数（BIN）系统来调查加拿大1,800多个地点的螨虫多样性，这些地点主要来自土壤和垃圾栖息地，而淡水，植物和动物寄主的贡献较小。来自73,394个标本的条形码揭示了7,077个BIN，其中包括所有四个订单（Ixodida，Mesostigmata，Sarcoptiformes，菱形）和60％（186）的已知家庭。BIN总数是先前从加拿大记录的物种（2,999）的2.4倍，反映了几个家族出乎意料的高度丰富。丰富度预测表明，在采样地点将发生超过28,000个BIN，这表明加拿大螨虫的动物群几乎可以肯定包括30,000多个物种，其总数与加拿大最常见的昆虫纲Diptera相似。这种意想不到的多样性被划分为高度不同的，空间结构的组合，这些组合可能反映了分散限制和环境异质性。进一步采样更大范围的栖息地将有助于加深对加拿大螨类多样性的了解，但在其他地理区域进行类似分析对于确定全球范围内的螨类多样性也必不可少。