The striped eel catfish, Plotosus lineatus was first described by Thunberg in 1787 from the Indo-Pacific region in the East Indian Ocean. Since then, the species has been recorded in various marine and brackish habitats in Japan, southern Korea, the Ogasawara Islands, Australia, Lord Howe Island, Palau and Yap in Micronesia, East Africa to Samoa, Madagascar, Red Sea and the Persian Gulf. Occurrences of this species have also been registered in the Mediterranean Sea, a non-native location, indicating a possible biological invasion event. Despite its long history, the taxonomic status of the P. lineatus species complex remains puzzling and uncertain. Here, we analysed all the available mitochondrial cytochrome c oxidase subunit 1 sequences (NCBI and BOLD) from specimens covering the current known distribution range, in an attempt to clarify the evolutionary relationships of different lineages within this species. We deduce nine monophyletic Lineages - I–IX, of P. lineatus with Kimura-2P distances ranging from 2% to 16%, with a mean intraspecific distance of 6%. Strikingly, Lineage V is composed uniquely of Mediterranean-captured individuals, with an unknown evolutionary origin. These findings strongly suggest the need for a careful species taxonomic reassessment. Some Lineages are composed of individuals from specific geographic locations (e.g., Australia and Indonesia), while others include specimens from broader geographic areas (e.g., almost all Indo-Pacific coastline). Additionally, several deposited sequences are most likely the result of morphology-based misidentifications. Due to the biological invasive potential, as well as the use of the species as a valuable physiology model, the P. lineatus species complex requires further attention. Overall our study offers a clear framework for future comparative studies of striped eel catfish individuals captured from different ecosystems.

条纹鳗鲶鱼Plotosus lineatus于 1787 年由 Thunberg 在东印度洋的印度太平洋地区首次描述。从那时起，该物种在日本、韩国南部、小笠原群岛、澳大利亚、豪勋爵岛、帕劳群岛和密克罗尼西亚雅浦岛、东非到萨摩亚、马达加斯加、红海和波斯湾的各种海洋和咸水栖息地都有记录。该物种也曾在地中海这一非本土地区出现过，表明可能存在生物入侵事件。尽管历史悠久，P. lineatus的分类地位物种复杂性仍然令人困惑和不确定。在这里，我们分析了涵盖当前已知分布范围的标本中所有可用的线粒体细胞色素c氧化酶亚基1序列（NCBI和BOLD），试图阐明该物种内不同谱系的进化关系。我们推断出P. lineatus的九个单系谱系- I–IX，其Kimura-2P 距离范围为 2% 至 16%，平均种内距离为 6%。引人注目的是，世系 V是由地中海捕获的个体组成的，其进化起源未知。这些发现强烈表明需要进行仔细的物种分类学重新评估。一些血统由来自特定地理位置（例如澳大利亚和印度尼西亚）的个体组成，而其他则包括来自更广泛地理区域（例如几乎所有印度太平洋海岸线）的样本。此外，一些沉积的序列很可能是基于形态学的错误识别的结果。由于生物入侵潜力，以及将该物种用作有价值的生理学模型，P. lineatus物种复合体需要进一步关注。总的来说，我们的研究为未来从不同生态系统捕获的条纹鳗鲶鱼个体的比较研究提供了一个清晰的框架。