Phylum: Charophyta   Family: Desmidiaceae

Cosmarium ausseeanum (R. Lenzenweger) F.A.C. Kouwets 2025

A very small cell with hexagonal semicells, the lower part of the sides broadly rounded and divergent, the upper part of the sides converging and retuse. Apices truncate with sharp angles. Small granules occur at the median point of the sides and at the apical angle. There is also a granule just below the apex, centrally placed, this is best observed in apical view. It needs to be carefully compared with C. obtusius (Gutwinski) Kouwets 2025, but that species lacks the apical granules. A zygospore found at Askernish, South Uist is the first recorded.
Cell dimensions: L: 7.4-8.2 µm; B: 7.7-8.5 µm; Is: 2.2-2.4 µm; Th: 4.8-4.9 µm; L/B: 0.96-0.97.
Zygospore minus projections: 10.1 x 7.7 µm; projections with an inflated base: 4.0-5.5 µm.
A rare desmid found in the tychoplankton of shallow pools and lochans. Only known from two localities in Europe and one in the Outer Hebrides.

References: 
Kouwets, F.A.C. (2025). European Flora of the Desmid Genus Cosmarium. Part 1: Text. Part 2: Plates