Research Institute for Global Change (RIGC), Japan Agency for Marine-Earth Science and Technology (JAMSTEC), Yokosuka, Kanagawa 237-0061, Japan.
Sugashima Marine Biological Laboratory, Graduate School of Science, Nagoya University, Sugashima, Toba, Mie 517-0004, Japan.
Biol Lett. 2024 Jul;20(7):20230573. doi: 10.1098/rsbl.2023.0573. Epub 2024 Jul 31.
Chemosynthesis-based ecosystems such as hydrothermal vents and hydrocarbon seeps harbour various endemic species, each uniquely adapted to the extreme conditions. While some species rely on obligatory relationships with bacterial symbionts for nutrient uptake, scavengers and predators also play important roles in food web dynamics in these ecosystems. Acoels, members of the phylum Xenacoelomorpha, are simple, worm-like invertebrates found in marine environments worldwide but are scarcely understood taxa. This study presents a novel genus and species of acoel from a deep-sea hydrocarbon seep off Hatsushima, Japan, gen. et sp. nov. Our multi-locus phylogenetic analysis revealed that the acoels are nested within Hofsteniidae, a family previously known exclusively from shallow waters. This finding suggests that at least two independent colonization events occurred in the chemosynthesis-based environments from the phylum Xenoacoelomorpha, represented by hofsteniid acoels and . Previous reports of hofsteniid species from low-oxygen and sulfide-rich environments, including intertidal habitats with decomposing leaves, in addition to gen. et sp. nov. from a deep-sea hydrocarbon seep, imply a common ancestral adaptation to sulfide-rich ecosystems within Hofsteniidae. Moreover, the sister relationship between solenofilomorphid acoels predominating in sulfide-rich habitats indicates common ancestral adaptation to sulfide-rich ecosystems between these two families.
基于化能合成的生态系统，如热液喷口和烃渗漏区，栖息着各种特有物种，每个物种都独特地适应极端环境。虽然有些物种依赖于与细菌共生体的强制性关系来获取营养，但清道夫和捕食者在这些生态系统的食物网动态中也起着重要作用。扁形动物门 Xenacoelomorpha 的成员是在全球海洋环境中发现的简单、蠕虫状的无脊椎动物，但它们是了解甚少的分类群。本研究描述了一种来自日本端岛深海烃渗漏区的新型扁形动物门扁形动物，属名和种名。我们的多基因座系统发育分析表明，扁形动物门被嵌套在 Hofsteniidae 科内，该科以前仅在浅水区被发现。这一发现表明，至少有两次独立的殖民事件发生在化能合成环境中，代表物是 Hofsteniidae 扁形动物门和。以前曾报道过 Hofsteniidae 物种存在于低氧和富含硫的环境中，包括有分解叶子的潮间带栖息地，以及新发现的深海烃渗漏区的属名和种名，这表明 Hofsteniidae 科内的物种具有共同的祖先适应富含硫的生态系统。此外，在富含硫的栖息地中占主导地位的 solenofilomorphid 扁形动物门的姐妹关系表明，这两个科之间存在共同的祖先适应富含硫的生态系统。
