Graduate School of Global and Environmental Studies, Kyoto University, Kyoto, Japan.
Graduate School of Human and Environmental Studies, Kyoto University, Kyoto, Japan.
PeerJ. 2022 Aug 26;10:e13891. doi: 10.7717/peerj.13891. eCollection 2022.
is a lotic-breeding salamander endemic to Shikoku Island in western Japan. Significant allozymic and morphological differences have been found among the populations of this species; however, the degree and pattern of intraspecific variation have not been surveyed using a sufficient number of samples.
For the taxonomic revision of , we conducted genetic and morphological surveys using samples collected throughout the distribution. Phylogenetic analysis using the cytochrome region of mitochondrial DNA and population structure analysis using single nucleotide polymorphisms were conducted to evaluate the population structure within the species and the degree of genetic differentiation. Subsequently, a morphological survey based on multivariate and univariate analyses was performed to assess the morphological variation.
Genetic analyses revealed three genetic groups (Tsurugi, Central, and Nanyo) within , with the Nanyo group distributed allopatrically from the others, and the Tsurugi and Central groups distributed parapatrically with the formation of a hybrid zone between them. The Nanyo group was morphologically distinguishable from the remaining samples, including the topotype of , based on a smaller body size and several ratio values of characters to snout-vent length, longer axilla-groin distance, shorter tail length, shorter internarial distance, longer upper eyelid length, and larger medial tail width. These results support the notion that the Nanyo group is an undescribed species. However, the remaining genetically differentiated groups could not be divided in the present study. Herein, we described the Nanyo group as a new species.
山椒鱼是一种分布在日本西部四国岛的急流型繁殖蝾螈。该物种的种群间存在显著的同工酶和形态差异；然而，尚未使用足够数量的样本对其种内变异程度和模式进行调查。
为了对山椒鱼进行分类修订，我们在其分布范围内采集样本进行遗传和形态调查。利用线粒体 DNA 的细胞色素 b 区域进行系统发育分析，并利用单核苷酸多态性进行种群结构分析，以评估该物种内的种群结构和遗传分化程度。随后，进行了基于多元和单变量分析的形态调查，以评估形态变异。
遗传分析显示，山椒鱼内存在三个遗传群（刀根、中央和南海），南海群与其他群完全分布，而刀根和中央群分布于近缘，两者之间形成了一个杂交区。南海群在形态上与其他样本（包括模式产地的样本）不同，其体型较小，以及一些特征与体长的比值、腋胯距离较长、尾长较短、鼻间距离较短、上眼睑较长和中尾宽较大。这些结果支持南海群是一个未被描述的物种的观点。然而，在本研究中，其余遗传分化的群体无法进一步划分。在此，我们将南海群描述为一个新物种。
