Phylum: Charophyta   Family: Desmidiaceae

Cosmarium clepsydra morpha 

Cells small, mostly slightly longer than broad. Isthmus elongate, sinus open with a rounded apex, about parallel to start then open outwards. Semicells elliptic with broadly rounded lateral sides merging smoothly into the basal and apical angles. Apex gradually raise to a central shallow peak. No side or apical view has been observed. The cell-wall is foveate, but any other distinguishing features are masked by the furcoid chloroplast with a single pyrenoid per semicell.
This cell is superficially similar to Cosmarium clepsydra Nordstedt 1870 but differs in its open sinus, elliptical semicell shape with peaked apex and a broader isthmus.
The first and third plate below are representative, the others are still developing.
Cell dimensions: L: 23.4-25.8 µm. B: 21.9-23.9 µm. Is: 7.4-8.1 µm. L/B: 1.01-1.13.
Only known from a single mesotrophic loch with marginal vegetation comprising Eleocharis palustris, Equisetum fluviatile and Ranunculus flammula. More finds are needed to take this further.

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