Chamnansinp Atchaneey, Li Yang, Lundholm Nina, Moestrup Øjvind
Section of Marine Biology, Institute of Biology, University of Copenhagen, Øster Farimagsgade 2D, Copenhagen K, DK-1353, Denmark.
Department of Biology, Faculty of Science, Ramkhamhaeng University, Bangkok, 10240, Thailand.
J Phycol. 2013 Dec;49(6):1128-41. doi: 10.1111/jpy.12121. Epub 2013 Nov 8.
Marine phytoplankton samples containing diatoms of the Chaetoceros socialis group were collected from Thailand, China, Denmark, and Greenland, and cells were isolated into culture for light and electron microscopy and DNA sequencing of D1-D3 of the LSU rDNA. Species of this lineage are characterized by three short and one long setae extending from each cell, the long setae from several cells joining into a common center to form large colonies, which are sometimes visible with the naked eye. Phylogenetic analyses including sequences from other parts of the world revealed segregation into three groups. Most sequences fell into two large clades, one comprising material from cold waters, whereas the other contained material from warmer waters. Strain CCMP 172 from the Strait of Georgia, Washington State, USA, formed a separate group. The warm-water species included Chinese and Thai material and therefore probably also material from the type locality of C. socialis, Hong Kong. It is characterized by all setae being covered by spines and the setae extending from the valve at some distance from the margin. In the resting spores, both valves are ornamented with spines. The cold-water material is characterized by three spiny and one mostly smooth long setae, and the setae extend from the valve near the margin. Both valves of the resting spore are smooth. This material is described as C. gelidus sp. nov. C. radians, described from the Baltic in 1894, is considered a synonym of C. socialis. CCMP172 is in many ways intermediate and probably constitutes a separate species. The published evidence on this globally distributed and sometimes bloom-forming group of species indicates higher species diversity than presently thought.
从泰国、中国、丹麦和格陵兰收集了含有群居角毛藻属硅藻的海洋浮游植物样本，并将细胞分离培养用于光学和电子显微镜观察以及 LSU rDNA D1-D3 的 DNA 测序。该谱系的物种特征是每个细胞伸出三根短刚毛和一根长刚毛，几根细胞的长刚毛连接到一个共同中心形成大的群体，有时肉眼可见。包括来自世界其他地区序列的系统发育分析显示分为三组。大多数序列分为两个大分支，一个包含来自冷水的材料，另一个包含来自温暖水域的材料。来自美国华盛顿州乔治亚海峡的 CCMP 172 菌株形成一个单独的组。暖水物种包括来自中国和泰国的材料，因此可能也包括群居角毛藻模式产地香港的材料。其特征是所有刚毛都覆盖有刺，且刚毛从瓣壳边缘一定距离处伸出。在休眠孢子中，两个瓣壳都有刺装饰。冷水材料的特征是三根有刺的和一根大多光滑的长刚毛，且刚毛从靠近边缘的瓣壳伸出。休眠孢子的两个瓣壳都是光滑的。这种材料被描述为新物种冷角毛藻。1894 年从波罗的海描述的辐射角毛藻被认为是群居角毛藻的同义词。CCMP172 在许多方面处于中间状态，可能构成一个单独的物种。关于这个全球分布且有时形成水华的物种组的已发表证据表明物种多样性比目前认为的更高。
