Phylum: Charophyta   Family: Mesoteaniaceae

Spirotaenia beijerinckii P.F.M. Coesel 2002

First described and illustrated by Lütkemüller (1903: 402, pl. 11: 2) as Spirotaenia minuta var. obtusa. More recently, Coesel (2002: 72, figs. 18-20) raised it to species level. Named in honour of Willen Beijerink whose illustration and description (Beijerink, 1926: 49, pl. 8: 164) as S. fusiformis is almost certainly identical to Lütkemüller’s S. minuta var. obtusa.
Cell dimensions: L: 25-47 µm; B: 3.5-6.0 µm; L/B: 6-10.
Coesel comments: “… was rather frequently encountered between submerged Sphagnum cuspidatum and Juncus bulbosus in some moorland pools …” Because of earlier confusion with the taxonomy, the status in the Outer Hebrides is uncertain.

References: 
Beijerinck, W. (1926) Over verspreiding en periodiciteit van zoetwaterwieren in Drentsche heideplassen.
Coesel, P.F.M (2002) New, intriguing desmid taxa from the Netherlands.
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.