The cladoceran Holopedium gibberum Zaddach, 1855 (Ctenopoda: Holopediidae) was once thought to occur broadly in the northern hemisphere, but its cryptic sister species was recently separated from H. gibberum sensu stricto (s.s.) as a new species, Holopedium glacialis. In East Asia, although “H. gibberum” occurrence has been recorded in many water bodies, the identity of the surveyed populations has rarely been confirmed via molecular analyses. Thus, it is unclear whether it is actually H. gibberum s.s. or H. glacialis that is distributed in East Asia. We used DNA-barcoding techniques to check the taxonomic status of Holopedium samples collected in Japan. We sequenced mitochondrial cytochrome c oxidase subunit 1 (mtCOI) and nuclear 18S ribosomal DNA (nr18S) of Japanese Holopedium and compared the results with those of H. gibberum s.s. collected in Norway and H. glacialis collected in Canada. The mtCOI sequence divergences between Norwegian H. gibberum s.s. and Japanese Holopedium were at most 2.4%, which was within the degree of intraspecific differentiation in cladocerans. Norwegian H. gibberum s.s. and Japanese Holopedium shared identical nr18S haplotypes. Individuals of Canadian H. glacialis were genetically different from those of Japanese Holopedium. We therefore concluded that Japanese Holopedium can be identified as H. gibberum s.s.

中文翻译：

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形态学和遗传学分析证实了亚洲菊科植物（甲壳纲：Cladocera）的分类位置

曾被认为是锁角形的霍第氏小球藻Zaddach，1855年（Ctenopoda：Holopediidae）广泛分布于北半球，但最近它的隐性姊妹物种被分离为一种新的命名为H. gibberum sensu stricto（ss）的霍氏霍德氏球菌。在东亚，尽管在许多水体中都记录了“赤霉菌”的发生，但很少通过分子分析来确认所调查种群的身份。因此，目前还不清楚是否真H. gibberum SS或H.冰川是分布于东亚。我们使用了DNA条形码技术来检查Ho形目的分类状态在日本收集的样品。我们测序的线粒体细胞色素c ^氧化酶1（mtCOI）和核18S核糖体日本的DNA（nr18S）Holopedium并与这些结果H. gibberum在挪威和收集SS H.冰川收集在加拿大。挪威H. gibberum ss和日本Holopedium的mtCOI序列差异最多为2.4％，在锁骨蟹种内分化程度之内。挪威H. gibberum ss和日本Holopedium具有相同的nr18S单倍型。加拿大H. glacialis个体在基因上与日本霍氏菌属有差异。因此，我们得出的结论是，可以将日本虎耳草属植物鉴定为H. gibberum ss