ABSTRACT The Japanese otter (Lutra nippon), once inhabited in most islands of Japan, is now considered as an extinct species. Although the Japanese otter is regarded as a distinct species from the Eurasian otter (L. lutra), its phylogeny and taxonomic status are based on limited information on morphological and genetic data, and thus further clarification is required. Here, we assessed the phylogenetic relationship among the genus Lutra and taxonomic status of L. nippon by using the complete sequences of cytochrome b gene of its holotype. The present phylogenic trees supported that the genus Lutra specimens largely formed monophyletic group, with L. sumatrana as a basal to other Lutra species. Within Lutra species, L. nippon was distantly related with L. lutra. The European otter population of L. l. lutra were clustered together with its subspecies, L. l. chinensis rather than the same subspecies, Korean otter population. The discrepancy between the genetic data and traditional taxonomy justifies the necessity of reexamination of the current subspecific classification system of Eurasian otters. Level of genetic divergence between the holotype of L. nippon and L. lutra was two to three-fold lower than those among the other sister species of the Lutrinae. Based on the level of divergence between the L. nippon and L. lutra, and insufficient evidence of morphological difference between them, it is suggested that designation of Japanese otter as a separate species from L. lutra will be reconsidered.

中文翻译：

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基于分子证据的东亚水獭物种的分类地位是什么？：聚焦博物馆日本水獭正模标本的位置

摘要 日本水獭 (Lutra nippon) 曾经栖息在日本的大部分岛屿，现在已被视为已灭绝的物种。虽然日本水獭被认为是与欧亚水獭 (L. lutra) 不同的物种，但其系统发育和分类地位基于形态学和遗传数据的有限信息，因此需要进一步澄清。在这里，我们通过使用其正模的细胞色素 b 基因的完整序列评估了 Lutra 属与 L. nippon 分类地位之间的系统发育关系。目前的系统发育树支持了 Lutra 属标本主要形成单系群，L. sumatrana 作为其他 Lutra 物种的基础。在 Lutra 物种中，L. nippon 与 L. lutra 有远亲关系。L. l. 的欧洲水獭种群 lutra 与其亚种 L. l. chinensis 而不是同一个亚种，韩国水獭种群。遗传数据与传统分类学之间的差异证明了重新检查欧亚水獭当前亚种分类系统的必要性。L. nippon 和 L. lutra 正模之间的遗传差异水平比 Lutrinae 的其他姐妹物种低两到三倍。基于 L. nippon 和 L. lutra 之间的差异程度，以及它们之间形态差异的证据不足，建议重新考虑将日本水獭指定为与 L. lutra 不同的物种。遗传数据与传统分类学之间的差异证明了重新检查欧亚水獭当前亚种分类系统的必要性。L. nippon 和 L. lutra 正模之间的遗传差异水平比 Lutrinae 的其他姐妹物种低两到三倍。基于 L. nippon 和 L. lutra 之间的差异程度，以及它们之间形态差异的证据不足，建议重新考虑将日本水獭指定为与 L. lutra 不同的物种。遗传数据与传统分类学之间的差异证明了重新检查欧亚水獭当前亚种分类系统的必要性。L. nippon 和 L. lutra 正模之间的遗传差异水平比 Lutrinae 的其他姐妹物种低两到三倍。基于 L. nippon 和 L. lutra 之间的差异程度，以及它们之间形态差异的证据不足，建议重新考虑将日本水獭指定为与 L. lutra 不同的物种。