采自青海湖的刚毛藻属一新种——青海刚毛藻

THE IDENTIFICATION OF CLADOPHORA QINGHAIENSIS SP.NOV.,WITHIN THE GENUS CLADOPHORA COLLECTED FROM QINGHAI LAKE,CHINA

对青海湖的丝状藻类进行了样品采集,分析引起水华的藻类种类和组成。基于SSU-LSU的联合进化分析和基于ITS的系统进化分析显示:形成青海湖水华的丝状藻为一种刚毛藻,该种与史氏刚毛藻Cladophora stimpsonii和散束刚毛藻Cladophora vagabunda具有较近的亲缘关系,属于海洋刚毛藻和淡水刚毛藻的中间过渡种类。和邻近种类的区别特征如下:该种生长于咸水生境,植物体纤细柔软,呈绿色或浅绿色,分枝旺盛,具明显的顶端生长和居间生长。细胞直径较小。主轴细胞直径30.0—90.0μm,细胞长宽比2.4—8.0。分枝细胞直径25.0—70.0μm,长宽比4.0—12.3。顶端细胞直径25.0—50.0μm,长宽比3.6—12.0。基于形态学特征和分子系统发育分析,将其定为一新种,即青海刚毛藻Cladophora qinghaiensis sp. nov.。

Since 2013,there have been frequent outbreaks of filamentous algal blooms in Qinghai Lake from July to September every year.Blooms not only affect the growth of phytoplankton,but also adversely impact tourism.In this study,we collected bloom samples from Qinghai Lake and identified the species type.All specimens were observed with light microscope.The individual molecular phylogeny based on internal transcribed spacer(ITS)sequences and the concatenated molecular phylogenies based on small subunit ribosomal DNA(SSU),large subunit ribosomal DNA(LSU)were reconstructed.The results showed that these samples belonged to one Cladophora species.The species is closely related with Cladophora stimpsoniiand and Cladophora vagabunda,and belongs to the transition type from ocean to freshwater.Several characteristics can be used to distinguish it from similar Cladophora species:Plants live in brackish habitat,densely branched,slender and soft with typical intercalary and acropetal growth.Filaments,light green to bright green,have smaller cell-diameters.The cell diameter of main axes is about 30—90.0μm with a L/D ratio of 2.4—8.0.The diameter of ultimate branches is 25.0—70.0μm with a L/D ratio of 4.0—12.3.The diameter of apical cells is 25.0—50.0μm with a L/D ratio of 3.6—12.0.On the basis of the morphological and phylogenetic analyses,we propose a new species,Cladophora qinghaiensis sp.nov.