Phylum: Charophyta   Family: Mesotaeniaceae

Netrium minutum S. Ohtani 1990

A widespread species covering areas of Europe, Asia and North America. According to Ohtani (1990) there is an almost complete size-overlay with N. lanceolatum so it is better to rely on shape. N. lanceolatum is, not surprisingly, lanceolate; N. minutum is elliptic. It would seem to occupy similar acidic habitats to N. digitus.

References: 
Ohtani, S. (1990) A Taxonomic Revision of the Genus Netrium (Zygnematales, Chlorophyceae).