Phylum: Charophyta   Family: Mesotaeniaceae

Netrium lanceolatum S. Ohtani 1990

First described and illustrated by Ohtani (1990: 36, 32-35). A widespread species: Tsarenko et al. (2014: 19) give distribution as; northern countries of Europe, Asia and North America. This would suggest a subarctic distribution.
Cell dimensions: L: 88-226 µm; B: 29-45 µm, L/B: 2.8-6.1.
Because of confusion with other Netrium species, its status in the Outer Hebrides is vague. Recent finds are from mildly acidic habitats such as abandoned peat-cuttings and shallow moorland pools. It has also been found with moss on wet rocks.

References: 
Ohtani, S. (1990). A Taxonomic Revision of the Genus Netrium (Zygnematales, Chlorophyceae).
Tsarenko, P.M., Wasser, S.P. & Nevo, E., editors,(2014). Algae of Ukraine, Volume 4: Charophyta.