Southernmost South America provides significant wintering habitats for migrant shorebirds, most of which breed in the High Arctic tundra. Helminth species parasitizing these migratory birds have been well studied in North America; however, in South America they are poorly known. As part of an ongoing research on the helminth fauna from Patagonian birds in Argentina, we report Notocotylus chionis and Notocotylus sp. (Trematoda: Notocotylidae) parasitizing three shorebird species, the Nearctic migrants Calidris fuscicollis (WRSA) and Calidris bairdii (BASA) (Scolopacidae), and the Neotropical Charadrius falklandicus (TBPL) (Charadriidae). We provide a new morphological description of N. chionis considering that the previous one reported from the snowy sheathbill on Subantarctic islands are incomplete and based on few specimens. We also provided a morphometric characterization of Notocotylus sp. We obtained molecular data which confirmed the identification of specimens recovered from WRSA and TBPL as N. chionis. Phylogenetic analysis based on 28S ribosomal DNA sequences was performed. The results placed N. chionis close to other Patagonian species native to South America (i.e. N. primulus). Notocotylus chionis was found previously in the snowy sheathbill which inhabits in coasts of southern South America, Antarctic Peninsula and surrounding islands. Present finding in resident birds (TBPL) allows us to hypothesize that N. chionis is a Neotropical species whose life cycle is being completed in southern South America and Subantarctic islands and represents a valuable contribution to the knowledge of parasite diversity in the austral subpolar region of the western hemisphere.

中文翻译：

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Notocotylus chionis (吸虫科：Notocotylidae) 和 Notocotylus sp。来自阿根廷巴塔哥尼亚南部湿地的滨鸟：形态和分子研究

南美洲最南端为迁徙的滨鸟提供了重要的越冬栖息地，其中大部分栖息在高北极苔原。北美对寄生于这些候鸟的蠕虫物种进行了深入研究。然而，在南美洲，它们鲜为人知。作为对阿根廷巴塔哥尼亚鸟类蠕虫动物群正在进行的研究的一部分，我们报告了 Notocotylus chionis 和 Notocotylus sp。（吸虫：Notocotylidae）寄生于三种滨鸟物种，即近北区迁徙者 Calidris fuscicollis (WRSA) 和 Calidris bairdii (BASA)（Scolopacidae），以及新热带 Charadrius falklandicus (TBPL)（Charadriidae）。我们提供了一种新的 N. chionis 形态学描述，因为之前从亚南极岛屿上的白雪皑皑的鞘嘴鸟中报告的形态不完整并且基于很少的标本。我们还提供了 Notocotylus sp 的形态学特征。我们获得的分子数据证实了从 WRSA 和 TBPL 中回收的标本是 N. chionis。进行了基于 28S 核糖体 DNA 序列的系统发育分析。结果使 N. chionis 与南美洲原产的其他巴塔哥尼亚物种（即 N. primulus）接近。Notocotylus chionis 以前曾在栖息在南美洲南部、南极半岛和周围岛屿的白雪皑皑的鞘嘴鸟中被发现。目前在留鸟 (TBPL) 中的发现使我们可以假设 N.