Phylum: Charophyta   Family: Spirogyracea

Spirogyra H.F. Link, 1820, nom. cons.

First described and illustrated by Link, 1820, nom. cons. [in] Nees (1820). A conserved name or nomen conservandum (abbreviated as nom. cons.) is a scientific name that has specific nomenclatural protection. That is, the name is retained, even though it violates one or more rules which would otherwise prevent it from being legitimate (see Turland 2019: 84). Conjugation is required to identify most species.
Cell dimensions: B: 8-160 µm (a huge range).
Very common in relatively clear eutrophic water, developing slimy filamentous green masses.

References: 
John, D.M., Whitton, B.A. & Brook, A.J. (2011 second edition). The Freshwater Algal Flora of the British Isles.
Link, H.F. [in] Nees, C.G (1820). Horae physicae Berolinenses collectae ex symbolis virorum doctorum H. Linkii...; edicuravit Christianus Godof. Nees ab Esenbeck.
Turland, N. (2019 second edition). The Code Decoded: a user's guide to the International Code of Nomenclature for algae, fungi, and plants.