菱形藻是较常见的羽纹硅藻类，其中一些种类的外部形态十分相似，差异细微，很难从经典形态分类的角度准确区分，造成此类微藻在分类地位上的混乱。作者综合利用经典形态分类方法、ITS（Internal transcribed spacer sequences）序列分析方法以及基于脂肪酸甾醇的化学分类多种方法，对4株从形态观察初步确定为菱形藻及其近缘种类的野外采集样品以及在分类上仍存分歧的小新月菱形藻（Nitzschia closterium f.minutissima）和三角褐脂藻（Phaeodactylum tricornutum），进行了几种易混淆种类界定的差异比较研究。结果显示，基于多种方法的微藻种类鉴定，能获取比单一鉴定方法更多的鉴定信息，并且几种方法能获得比较一致的结果；分别明确了野外水样中的四株微藻品系的分类地位，其中的3株分别为拟尖刺菱形藻（Pseudo—nitzschia pungens Hasle）、柔弱拟菱形藻（Pseudo—nitzschia delicatissima）、新月筒柱藻（Cylindrotheca closterium），但另外一株仅能确定为细柱藻属的一种，仍不能鉴定到种。分析结果还表明，小新月菱形藻应属于舟形藻目，褐指藻科，褐指藻属，这与之前有学者报道的结果一致。%Nitzschia spp. belongs to a common group of pennate diatom. Some species in this genus have subtle morphological differences, which make them difficult to be properly identified based on their morphological profiles only. In this paper, three taxonomical methods, namely microscopy observation, internal transcribed spacer sequence （ITS） sequence analysis, and microalgal fatty acids and sterols analysis, were used in the study of four field samples, which were preliminary identified to be Nitzschia genus and two closely related species, i.e., Nitzschia closterium f Minutissima and Phaeodactylum tricornutum, using morphological method. We found that more information could be obtained by applying multiple methods in identifying microalgal strains than using only one method. Similar taxonomic results were obtained using these three methods. From the study, three field samples were identified to be Pseudo-nitzschia pungens Hasle, Pseudo-nitzschia delicatissima, and Cylindrotheca closterium, respectively. However, we were only able to identify to the fourth strain as Cylindrotheca genus. The results also showed that Nitzschia closterium f Minutissim belongs to Naviculales, Phaeodactylaceae, Phaeodactylum, consistent with previous findings.
展开▼
