Sepioteuthis lessoniana is a crucial squid species in fisheries and plays a critical role in marine ecosystems. At least two taxa of the squid species have been identified in the waters around Japan; however, the basic biological information of these taxa is limited. In this study, the taxa composition of Sepioteuthis was examined using molecular evidence, and the life-history traits and statolith shape of these taxa were analyzed to elucidate the potential population structure. A total of 142 squid samples were collected from six locations around Nagasaki (southwestern Japan) where high taxonomic diversity has been found previously. Three taxa (Sepioteuthis sp. 1, sp. 2, and sp. 2A) were identified based on the mitochondrial cytochrome oxidase c subunit I (COI) gene, among which Sepioteuthis sp. 2A was defined for the first time. Sepioteuthis sp. 2 was predominant in the region (average occurrence rate 84%), whereas Sepioteuthis sp. 1 was rare, with only two individuals found near Goto Islands. The mantle length composition, mantle length–body weight relationship, age structure, and average growth rates were similar between Sepioteuthis sp. 2 and sp. 2A. However, Sepioteuthis sp. 2 mainly hatched during summer (June–July), whereas Sepioteuthis sp. 2A hatched during winter (December–February). The statolith shapes of the squids were similar between the taxa, although slight differences were noted in the wing regions. The three taxa largely overlapped in a principal component analysis bi-plot based on variations extracted from five life-history traits. These results suggest that at least three taxa of Sepioteuthis inhabited the region, although few differences were found between them in life-history traits or statolith shapes that might be substantially influenced by regional oceanographic conditions. This study provides essential information on the population structure and connectivity of the squid, which is crucial in the context of conservation and management measures for fisheries.

Sepioteuthis lessoniana是渔业中的重要鱿鱼种类，在海洋生态系统中起着关键作用。在日本周围的水域中，至少发现了两个鱿鱼种类的分类单元。但是，这些分类单元的基本生物学信息是有限的。在这项研究中，类群组成Sepioteuthis利用分子证据进行了检查，并分析生活史特性和这些类群的耳石形状，以阐明潜在的人口结构。从长崎（日本西南部）附近的六个地点收集了总共142个鱿鱼样品，这些地方以前已经发现了高分类学多样性。三个分类单元（Sepioteuthissp。1，sp。2，sp。2A）是根据线粒体细胞色素氧化酶c亚基I（COI）基因鉴定的，其中Sepioteuthis sp。2A是第一次定义。Sepioteuthis sp。该地区以2为主，平均发生率为84％，而Sepioteuthis sp。1个罕见，只有五个人在五岛群岛附近被发现。Sepioteuthis sp。的地幔长度组成，地幔长度与体重的关系，年龄结构和平均增长率相似。2和sp。2A。但是，Sepioteuthis sp。2主要在夏季（6月至7月）孵化，而Sepioteuthissp。2A在冬季（12月至2月）孵化。鱿鱼的鳞茎形状在各类群之间是相似的，尽管在机翼区域发现了些微差异。基于从五个生命历史特征中提取的变异，这三个分类单元在主成分分析双图中有很大的重叠。这些结果表明，该地区至少有三个乌贼属居住，尽管它们之间的生活史特征或石笋形状几乎没有差异，而这些差异可能受到区域海洋条件的影响。这项研究提供了有关鱿鱼种群结构和连通性的基本信息，这对于渔业的养护和管理措施至关重要。