利用透射电镜(TEM),对采自我国沿海海域的水样进行了观察,针对其中的海链藻属ThalassiosiraCleve开展了分类学的专题研究.经鉴定,确认其中的5个种类为我国的新记录种类,它们分别是安达曼海链藻T.andamanicaGedde、双线海链藻T.duostraPienaar、吉思纳海链藻T.gessneriHustedt、海氏海链藻T.hasleaeCassie et Dempsey和具毛海链藻T.hispidaSyvertsen.我们对每个种类的形态学特征、生活习性和生态分布进行了说明,并提供了电镜照片.
Protokeelia is described as a new and rare pennate diatom genus in China.Its valve includes two parts:ventral valve and dorsal valve.The ventral valve is more or less convex or concave.The raphe runs in a distinct elevated and thickened siliceous ridge.In the internal valve,beneath the raphe are fibulae or fibulae clusters which connect the ventral and dorsal valves.One species,P.spinifera Round & Basson,is observed in the water samples from a mangrove forest in Sai Kung,Hong Kong,China.Its main morphological features are described in this paper along with electron microscope(EM) photos.Morphological comparisons are also made among several allied species.In addition,a newly recorded species for China,Rhopalodia iriomotensis Kobayasi,Nagumo & Tanaka,is discussed here.Because several key features observed in this species resemble those of some Pro-tokeelia species,we suggest that it may actually represent a Protokeelia species.
Marine nanoplanktonic diatoms have been frequently either underestimated or overlooked in phyto-plankton investigations due to their small size(2-20 μm),which allows most of them to pass through a regular phytoplankton net of 70-μm pore size.For nanoplanktonic diatom classification,water samples(each 2000 mL) were collected from several representative sea areas of Chinese coast from May 2002 to May 2006.Pelagodictyon Clarke was identified as a newly recorded nanodiatom genus for China under transmission electron microscope(TEM).This genus is characterized by the delicate structure of the valve face.The striae are seen to be formed by ribs with cross-ribs(frets) and the intervening spaces are occupied by polygonal cribra situated much close to the exterior face of the valve.Just one species was found,i.e.,P.tenue Clarke.Detailed description of the taxonomic characteristics with TEM photographs of this species and its ecological habitat and distribution are given in this paper.Morphological characteristics comparisons among several resembling genera were discussed.
