硅藻中国新记录种——帕瓦拉桥弯藻

Cymbella pavanaensis A.Vigneshwaran et al.,a diatom reported for the first time in China

在对湖南省硅藻多样性研究过程中,发现其中一采自湘江的桥弯藻种类具有以下鉴定特征:(1)细胞小,长度小于29μm;(2)壳面略微呈背腹之分;(3)远缝端末梢向壳面背侧弯曲;(4)顶孔区很小,由1~3横列形态不同的两种类型孔纹组成,一种孔纹与壳面上的孔纹相似,呈狭缝隙状,另一种为圆形小孔,其内部开口上方有袋盖状硅质突出物覆盖;(5)壳面背侧中部处线纹密度每10μm为10~12条、腹侧中部处每10μm为11~13条,孔纹密度每10μm为30~40个;(6)在靠近壳面腹侧中央区具有1~2个孤点。经与帕瓦拉桥弯藻(Cymbella pavanaensis A.Vigneshwaran et al.)模式种群相比较,该文确定上述桥弯藻即为帕瓦拉桥弯藻。该文提供了对帕瓦拉桥弯藻超微结构的更多清晰认识,扩大了其地理分布区域,且是该种在中国的首次报道。

During the process of studying the diatom diversity of Hunan Province,we find that a Cymbella species collected from Xiang River possesses the following diagnostic features:(1)Cells are small and their lengths are less than 29μm;(2)Valves exhibit slight dorsiventrality;(3)Distal raphe fissures are dorsally deflected;(4)Apical pore fields are very small and composed of 1-3 transapical rows of porelli,which comprise two forms,one is slit-like,similar to the areolae on the valve face,and the other is rounded with internal openings covered by the flap-like silica projections;(5)Striae 10-12/10μm at the dorsal middle part,11-13/10μm at the ventral middle part,and areolae 30-40/10μm;(6)And 1-2 stigmata exist near the valve ventral central area.After comparing this species with the type population of Cymbella pavanaensis A.Vigneshwaran et al.,in this paper,it is identified as C.pavanaensis.This paper provides a clearer knowledge of the ultrastructure of C.pavanaensis,enlarges its geographical distribution region,and reports it for the first time in China.