3种淡水布纹藻(硅藻纲)的超微结构研究

该研究利用光学和扫描电子显微镜对3种淡水布纹藻(钝布纹藻、库氏布纹藻和赛欧托布纹藻)的形态学进行了研究，以明确它们的精细结构特征；并分析讨论它们在中国的地理分布区域。结果表明：(1) 3种淡水布纹藻皆属于粗糙布纹组；从壳面观看，都具有S形和反S(S)形两种壳瓣外形。(2) 钝布纹藻具有弱的S形壳面外形、T形的外近端壳缝末稍和直的内近端壳缝末稍以及椭圆形的中央区；库氏布纹藻具有明显的S形壳面外形、略微向不同侧偏转的外近端壳缝末稍和直的内近端壳缝末稍以及椭圆形的中央区；赛欧托布纹藻具有弱的S形壳面外形、强烈钩状的外近端壳缝末稍和T形的内近端壳缝末稍以及倾斜的中央区。(3) 钝布纹藻在广东、广西、湖南、四川和云南等地有分布；库氏布纹藻在新疆和湖南等地有发现；赛欧托布纹藻分布于武陵山区，该文是其在中国淡水分布的首次报道。

Ultrastructure of Three Freshwater Species of Gyrosigma (Bacillariophyceae)

A morphology study is carried out on three freshwater species of Gyrosigma (Gyrosigma obtusatum, G. kuetzingii and G. sciotoense) using light and scanning electric microscopy to demonstrate their fine structural characters, and the regions of their geographical distribution in China are also summarized. The results show that: (1) all three species belong to the section Strigiles and all present two types of valve outline in valve view: S shaped and reverse S shaped (S shaped); (2) G. obtusatum has weakly sigmoid valve outline, T shaped external proximal raphe fissures, straight internal proximal raphe ending, and elliptic central area; G. kuetzingii bears distinctly sigmoid valve outline, external proximal raphe fissures which slightly deflect towards different sides, straight internal proximal raphe ending, and elliptic central area; and G. sciotoense possesses also weakly sigmoid valve outline, strongly hooked external proximal raphe fissures, T shaped internal proximal raphe fissures, and oblique central area; (3) G. obtusatum is found in Guangdong, Guangxi, Hunan, Sichuan and Yunnan; G. kuetzingii is found in both Xinjiang and Hunan; and G. sciotoense is only discovered in Wuling Mountains, and this is its first report from the freshwater in China.