Tardigrade diversity and distribution are enigmatic in most parts of the globe, and only some European countries can boast of a relatively well-studied water bear fauna. However, even these suffer from the lack of genetic data, which would substantiate faunistic data and make biogeographic comparisons easier. Denmark has never been intensively and systematically researched in this regard, thus a citizen science sampling of cryptogams (mosses, liverworts, and lichens) was launched in spring 2023, aiming at a comprehensive biodiversity survey across this insular country. Nearly 700 samples were selected out of 8.000 sent to NHMD, based on the quality of samples, representativeness of various regions of Denmark, and the type of substrate to allow unravelling of potential ecological associations between tardigrades and cryptogams. Importantly, a large fraction of morphological identifications was backed up by DNA barcode data based on ITS-2 (1001 sequences), and in some cases also on COI (93 sequences) and ITS-1 (22 sequences) molecular markers, which are recognised DNA fragments used in species delimitation. We quadruple the number of known Danish limno-terrestrial tardigrade species (55 spp. reported in this paper vs. 14 spp. reported in literature so far, most of which were contentious due to the insufficient knowledge on tardigrade taxonomy), demonstrating the power of integrative taxonomy. No fewer than nine spp. are new to science. This is the first case where tardigrade fauna of an entire country is examined both from morphological and DNA barcoding data perspective.

中文翻译：

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大规模公民科学采样和综合分类方法揭示了丹麦隐栖息的缓步动物群


缓步动物的多样性和分布在全球大部分地区都是个谜，只有一些欧洲国家可以拥有相对深入研究的水熊虫动物群。然而，即使是这些也缺乏遗传数据，而遗传数据将证实动物群数据并使生物地理学比较更容易。丹麦在这方面从未接受过深入和系统的研究，因此于 2023 年春季启动了隐花藻（苔藓、地衣和地衣）的公民科学采样，旨在在这个岛屿国家进行全面的生物多样性调查。根据样本的质量、丹麦各个地区的代表性和基质类型，从发送给 NHMD 的 700 个样本中选择了近 8.000 个样本，以揭示缓步动物和隐花动物之间的潜在生态关联。重要的是，很大一部分形态学鉴定得到了基于 ITS-2（1001 个序列）的 DNA 条形码数据的支持，在某些情况下还基于 COI（93 个序列）和 ITS-1（22 个序列）分子标记，它们是用于物种界定的公认 DNA 片段。我们将已知的丹麦 limno-ter-terrescular 缓步动物物种的数量增加了四倍（本文报道了 55 种，而迄今为止文献中报道了 14 种，其中大多数由于对缓步动物分类学的了解不足而存在争议），展示了综合分类学的力量。不少于 9 个 spp. 是科学的新物种。这是第一个从形态学和 DNA 条形码数据角度检查整个国家的缓步动物区系的案例。