Nematode species of the genus Contracaecum Railliet & Henry, 1912 have been reported around the world in many species of fish-eating birds and seals. Here, Contracaecum jorgei n. sp. is morphologically described using light and scanning electron microscopy for adults and fourth-stage larvae (L4) found in the bird Nannopterum brasilianus and third-stage larvae (L3) found in the freshwater fish Hoplias argentinensis, both from the province of Córdoba, Argentina. Additionally, sequences of cytochrome c oxidase subunit II were obtained from these specimens and molecular phylogenetic analysis was used to determine its relationships within the genus. The present species is distinguished from other species by the number and disposition of cephalic papillae; shape and size of the interlabia; length of the spicules; and number and arrangement of papillae in the posterior end of the male. Furthermore, in the molecular analyses, sequences obtained from adult L4 and L3 specimens of C. jorgei n. sp. were similar and grouped, forming an independent lineage, thus confirming it as a distinct species. Thus, morphological characteristics associated with molecular data support the proposal of a new species.

中文翻译：

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在南美洲发现寄生于巴西南翅目 (Suliformes: Phalacrocoracidae) 和 Hoplias argentinensis (Characiformes: Erythrinidae) 的一种新的 Contracaecum (线虫: Anisakidae): 幼虫和成虫阶段的形态和分子特征

该属的线虫种类盲肠Railliet & Henry, 1912 已在世界各地报道了许多以鱼为食的鸟类和海豹。这里，乔尔盖盲肠n. sp。使用光学和扫描电子显微镜对鸟类中发现的成虫和第四阶段幼虫 (L4) 进行形态学描述巴西南翅目和在淡水鱼中发现的第三阶段幼虫 (L3)阿根廷虎耳草，均来自阿根廷科尔多瓦省。此外，细胞色素序列C从这些标本中获得了氧化酶亚基II，并使用分子系统发育分析来确定其在该属内的关系。本种与其他种的区别在于头部乳头的数量和分布；阴唇的形状和大小；骨针的长度；雄性后端乳头的数量和排列。此外，在分子分析中，从成人 L4 和 L3 标本中获得的序列C.jorgein. sp。相似并分组，形成一个独立的谱系，从而确认它是一个独特的物种。因此，与分子数据相关的形态特征支持新物种的提议。