The coastline of Argentine Patagonia in the Southwest Atlantic provides highly productive habitats for a variety of aquatic birds. Both resident birds and migratory birds coming for wintering from the high arctic tundra, converge in these wetlands for resting and feeding, which favours parasite transmission. In the course of helminth diversity survey in Patagonian birds, we found a new digenean species belonging to the genus Parorchis (Philophthalmidae). Herein, we describe its complete life cycle and provide the morphological description accompanied by DNA sequence data. Adult specimens were obtained from the resident Kelp Gull Larus dominicanus (Laridae), and Nearctic migratory shorebirds, the Baird’s Sandpiper Calidris bairdii and the White-rumped Sandpiper Calidris fuscicollis (Scolopacidae). Rediae of the new species were found in the muricid gastropod Trophon geversianus (Muricidae), whose distribution is restricted to the intertidal and subtidal marine south coasts of Argentina and Chile. Sequences of complete ITS and partial 28S regions confirmed the conspecificity of the rediae from T. geversianus and adults specimens recovered from L. dominicanus and C. fuscicollis. Cercariae emerge from these molluscs and quickly encyst on the substrate including surfaces of the mollusc itself; shorebirds become infected by eating snails. We examine phylogenetic affinities of the new species using partial 28S sequences. Our analysis placed the new species in a clade with other Parorchis spp., which also use muricid gastropods as intermediate hosts. This study contributes to the knowledge of the diversity of marine trematodes in the subpolar region of South America.

西南大西洋的阿根廷巴塔哥尼亚海岸线为各种水鸟提供了高产栖息地。从北极高原苔原过冬的留鸟和候鸟都聚集在这些湿地休息和觅食，这有利于寄生虫的传播。在对巴塔哥尼亚鸟类的寄生虫多样性调查过程中，我们发现了一种新的寄生虫属寄生虫属（ Philophthalmidae）。在此，我们描述了它的完整生命周期，并提供了伴随 DNA 序列数据的形态学描述。成年标本取自常驻海带鸥Larus dominicanus（Laridae）和新北区迁徙滨鸟 Baird's Sandpiper Calidris bairdii和白腰鹬Calidris fuscicollis (Scolopacidae)。在腹足动物Trophon geversianus (Muricidae)中发现了新种的 Rediae ，其分布仅限于阿根廷和智利的潮间带和潮下带海洋南海岸。完整 ITS 和部​​分 28S 区域的序列证实了来自T. geversianus 的rediae和从L. dominicanus和C. fuscicollis中回收的成虫标本的同种特异性. 尾蚴从这些软体动物中长出，并迅速包囊在基质上，包括软体动物本身的表面；滨鸟因食用蜗牛而感染。我们使用部分 28S 序列检查新物种的系统发育亲和力。我们的分析将这个新物种与其他Parorchis spp. 放在一个进化枝中，后者也使用 muricid 腹足动物作为中间宿主。这项研究有助于了解南美洲次极地地区海洋吸虫的多样性。