Aulacoseira granulata var. angustissima– a filamentous centric diatom, a thin variant of the much more common type A. granulata. Cells usually < 5 um diameter as opposed to 9-16 um for the type. Another indicatory feature is that the points decorating the valve are hardly seen in this variety. Very rare in Lake Kinneret in recent years.
aalster and tzohary
A Alster & T Zohary, Kinneret Limnological Laboratory, IOLR
Photo taken with an Olympus BX50 Microscope equipped with DIC optics and PixeLink digital camera, mag. X40