Parasite diversity above the Arctic circle remains understudied even for commercially valuable host taxa. Thorny skate, Amblyraja radiata, is a common bycatch species with a growing commercial value. Its natural range covers both sides of the North Atlantic including the Arctic zone. Svalbard is a Norwegian archipelago located on the northwest corner of the Barents Shelf which sustains a spectacular species diversity. So far, several monogenean species have been reported infecting thorny skate across the Atlantic Ocean. In the present study, we intend to fill in the knowledge gap on monogenean parasites infecting thorny skate in the northern part of its range and thus indirectly assess the connectivity between the thorny skate populations off the Svalbard coast and from previously studied locations. 46 monogenean individuals were recovered from 11 specimens of thorny skate. Following morphological and molecular assessment, two species of monogeneans, Acanthocotyle verrilli and Rajonchocotyle emarginata, were identified. The results serve as the northernmost record for both parasite genera and the first record of monogenean species off Svalbard. Detailed morphometric evaluation revealed a relatively high level of morphological variation in A. verrilli compared to its congeners. Phylogenetic reconstruction placed A. verrilli in a well-supported clade with A. imo. Our study also suggests high diagnostic significance of sclerotised structures in the identification of Rajonchocotyle. Even though the occurrence of two directly transmitted parasite species supports the previously suggested long-distance migration of A. radiata, future studies employing highly variable genetic markers are needed to assess the ongoing and historical migration patterns.

中文翻译：

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寄生扁虫感染棘手的溜冰鞋，辐射的Amblyraja：斯瓦尔巴群岛的单生棘轮A和Rajonchocotyle emarginata感染

即使对于具有商业价值的宿主类群，北极圈上方的寄生虫多样性仍未得到充分研究。棘手的溜冰鞋，辐射伞，是常见的兼捕物种，具有越来越高的商业价值。它的自然范围涵盖北大西洋的两面，包括北极地区。斯瓦尔巴群岛是挪威群岛，位于巴伦支大陆架的西北角，保持着壮观的物种多样性。到目前为止，已经报道了几种单基因物种感染了横跨大西洋的棘手溜冰鞋。在本研究中，我们打算填补其范围北部感染棘轮滑冰的单基因寄生虫的知识空白，从而间接评估斯瓦尔巴特海岸外和以前研究过的棘轮滑冰种群之间的连通性。从11个棘手的滑冰样本中回收了46个单基因个体。经过形态和分子评估，发现了两种单基因菌，确定了棘皮棘皮小棘鱼和弓形棘皮小棘鱼。该结果是寄生虫属的最北记录，也是斯瓦尔巴特群岛外单属物种的第一个记录。详细的形态计量学评估显示，与同类动物相比，藜芦的形态变化水平较高。系统发生重建将A. verrilli与A. imo放在一个支撑良好的进化枝中。我们的研究还表明，硬化的结构在识别Rachochocotyle中具有很高的诊断意义。即使两个直接传播的寄生虫物种的出现支持了以前建议的辐射曲霉的长距离迁移，需要使用高度可变的遗传标记进行的未来研究来评估正在进行的迁移和历史迁移模式。