Phylum: Charophyta   Family: Mesotaeniacea

Spirotaenia oblonga J. Lütkemüller 1903

First described and illustrated by Lütkemüller (1903: 404, pl. 11: 8).
Cell dimensions: L: 20-31 µm; B: 6-7.5 µm; Is: L/B: 3-5.
A Europe-wide rare desmid. Occasionally found in oligotrophic waters.

References: 
Coesel, P.F.M. & Meesters, K.J. (2023 second edition). Desmids of the Lowlands.
Lütkemüller, J. (1903). Über die Gattungen Spirotaenia Bréb. II. Beschreibung neuer Arten und Bemerkungen über bekannte.