The Tardigrada are a clade with a disputed and complex taxonomy. The three traditional tardigrade classes are the Heterotardigrada, Eutardigrada and the dubious, monotypic Mesotardigrada. A recent molecular study by Guil et al (Zoologica Scripta, 48, 2019, 120) suggested that the Apochela, previously considered an order of Eutardigrada, should become a new class, Apotardigrada, with the Parachela becoming THE new Eutardigrada. This new diagnosis was presented alongside compelling morphological evidence. Here, we test the assumptions of the molecular evidence for Apotardigrada by analysing tardigrade 18S and 28S data under four separate conditions, along with new BUSCO data, across both Bayesian‐ and maximum‐likelihood phylogenetic approaches. We found variable conclusions regarding the status of Apotardigrada could be drawn by comparing the ribosomal RNA and BUSCO results, and caution against using branch length data to determine taxonomic hierarchy.

中文翻译：

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tardigrada的系统学：对tardigrade分类法的重新分析，具体参考Guil等人。（2019）

Tardigrada是一个有争议且复杂的分类法的进化枝。三种传统的tardigrade类别是Heterotardigrada，Eutardigrada和可疑的单型Mesotardigrada。Guil等人（Zoologica Scripta，48，2019，120）提出，以前被认为是Eutardigrada的订单的Apochela应该成为新的类Apotardigrada，而Parachela则成为THE New Eutardigrada。提出了这种新的诊断方法，同时提供了令人信服的形态学证据。在这里，我们通过分析贝叶斯和最大似然系统发育方法的四个单独条件下的缓坡18S和28S数据以及新的BUSCO数据，来检验Apotardigrada分子证据的假设。我们发现，通过比较核糖体RNA和BUSCO结果可以得出关于Apotardigrada状况的不同结论，并警告不要使用分支长度数据来确定分类学层次。