Taxonomic survey and DNA barcode library of tardigrades from alpine fens in northwestern Italy

Peatlands and peat-like habitats are among the most vulnerable ecosystems to climate change. Owing to their specific microclimatic conditions, which maintain high and stable moisture levels, they host assemblages dominated by hydrophilous taxa, including several groups of tardigrades. Despite this, tardigrade diversity in peat-related habitats remains poorly known. Here, we conducted an extensive taxonomic survey of tardigrades based on 35 samples collected from alpine fens in northern Italy. We detected 30 species-level tardigrade taxa, of which 23 were successfully DNA barcoded. One species of the genus Crenubiotus is new to science and is formally described herein as Crenubiotus meg sp. nov. We also provide updated morphological and taxonomic information for two enigmatic taxa, Fontourion secchii and Microhypsibius minimus, which have long been hindered by data deficiency. Notably, the assemblage recovered comprises several taxa with boreo-alpine or cold-adapted affinities, highlighting alpine peatlands as potential refugial habitats for relict tardigrade lineages. In addition, we performed phylogenetic analyses to resolve the placement of the newly described Crenubiotus species and to clarify the relationships of four Murrayon lineages recovered in this study. This work represents the first integrative taxonomic inventory of tardigrades inhabiting peat-like habitats and contributes an extensive, curated set of reference DNA sequences for this understudied habitat. These data provide an essential foundation for high-throughput biodiversity assessments using mega- and metabarcoding approaches and offer new insights into tardigrade taxonomy and evolutionary relationships.

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