DNA Barcoding Reveals High Cryptic Diversity in the North Eurasian <i>Moina</i> Species (Crustacea: Cladocera)

Species of the genus Moina Baird (Cladocera: Moinidae) often dominate freshwater crustacean communities in temporary water bodies. Several species of Moina are used as food for fish larvae in aquaculture, as bioindicators in toxicological studies, and as common subjects for physiological studies. The aim of this paper is to estimate biodiversity of Moina in northern Eurasia using the standard DNA barcoding approach based on the cytochrome c oxidase subunit I (COI) gene. We analysed 160 newly obtained and 157 existing COI sequences, and found evidence for 21 phylogroups of Moina, some of which were detected here for the first time. Our study confirmed the opinion that the actual species diversity of cladocerans is several times higher than is presently accepted. Our results also indicated that Moina has the second richest species diversity among the cladoceran genera (with only Daphnia O. F. Mueller having a greater diversity of species). Our study strongly supports division of Moina into two faunistic groups: European-Western Siberian and Eastern Siberian-Far Eastern, with a transitional zone at the Yenisey River basin (Eastern Siberia). Here, we refrain from taxonomic descriptions of new species, as this requires a thorough morphological and taxonomic study for each putative taxon.裸腹溞属（Moina Baird，枝角亚目：裸腹溞科（Moinidae））的物种常为暂时性水体淡水甲壳动物群落的优势类群。该属的多个物种被用作水产养殖中鱼类幼体的饵料、毒理学研究中的生物指示物，以及生理学研究的经典实验材料。本研究旨在基于细胞色素c氧化酶亚基I（cytochrome c oxidase subunit I，COI）基因的标准DNA条形码技术，评估欧亚大陆北部裸腹溞属的生物多样性。我们共分析了160条新获得的COI序列与157条已公开的COI序列，发现了21个裸腹溞属系统发育群，其中部分类群为本次研究首次报道。本研究印证了“枝角类实际物种多样性较当前认知高出数倍”这一观点。研究结果同时显示，在枝角类各属中，裸腹溞属的物种丰富度仅次于溞属（Daphnia O. F. Mueller）。本研究有力支持将裸腹溞属划分为两个区系类群：欧洲-西西伯利亚类群与东西伯利亚-远东类群，两者的过渡带位于叶尼塞河流域（东西伯利亚地区）。本次研究暂不进行新物种的分类学描述，因针对每一个推测类群均需开展详尽的形态学与分类学研究。