Lush ‘oases’ of life seen in chemosynthetic ecosystems such as hot vents and cold seeps represent rare, localized exceptions to the generally oligotrophic deep ocean floor. Organic falls, best known from sunken wood and whale carcasses, are additional sources of such oases. Kemp Caldera (59°42'S, 28°20'W) in the Weddell Sea exhibits active hydrothermal vents and a natural whale fall in close proximity, where an undescribed cocculinid limpet was found living in both types of chemosynthetic habitats. This represents the first member of the gastropod order Cocculinida discovered from hot vents, and also the first record from the Southern Ocean. Here, we applied an integrative taxonomy framework incorporating traditional dissection, electron microscopy, genetic sequencing and 3D anatomical reconstruction through synchrotron computed tomography in order to characterize this species. Together, our data revealed an unusual member of the genus Cocculina with a highly modified radula for feeding on bacterial film, described herein as Cocculina enigmadonta n. sp. Its phylogenetically derived position within the largely wood-inhabiting Cocculina indicates that it probably evolved from an ancestor adapted to living on sunken wood, providing a compelling case of the ‘stepping stone’ evolutionary trajectory from organic falls to seeps and vents.

中文翻译：

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从木头到通风口：在威德尔海发现的第一个与热液活动有关的球藻类帽贝

在热喷口和冷泉等化学合成生态系统中看到的茂盛生命“绿洲”代表了普遍贫营养的深海海底罕见的局部例外。以沉没的木材和鲸鱼尸体而闻名的有机瀑布是此类绿洲的额外来源。威德尔海的肯普火山口（59°42'S，28°20'W）展示了活跃的热液喷口和附近的天然鲸鱼坠落，在那里发现了一种未描述的球藻类帽贝，生活在两种化学合成栖息地中。这代表了从热喷口发现的第一个腹足类 Cocculinida 成员，也是南大洋的第一个记录。在这里，我们应用了一个综合分类框架，结合了传统的解剖、电子显微镜、通过同步加速器计算机断层扫描进行基因测序和 3D 解剖重建，以表征该物种。总之，我们的数据揭示了该属的一个不寻常的成员球菌属具有高度修饰的齿舌，用于以细菌膜为食，本文描述为神秘球菌n. sp。它在大部分木栖动物中的系统发育衍生位置球菌属表明它可能是从适应生活在沉没的木头上的祖先进化而来的，这提供了一个令人信服的例子，说明从有机瀑布到渗漏和通风口的“垫脚石”进化轨迹。