Phylum: Charophyta   Family: Closteriaciaea

Closterium angustatum var. gracilius Croasdale 1955

A very rare Arctic and northern species first discovered by Croasdale (1955) in Alaska. A few subsequent finds are from Sutherland, Scotland. It differs from the nominate variety by being significantly narrower. An acidophile of Sphagnum bogs and moorland peaty pools.

References: 
Croasdale, H.T. (1955) Freshwater algae of Alaska. 1. Some desmids from the interior.
Brook, A.J. & Williamson, D.B. (2010) A Monograph on some British Desmids.