Phylum: Charophyta Family: Desmidiaceae
Tetmemorus laevis var. minutus (A. de Bary) W. Krieger 1937
First described and illustrated by De Bary (1858: 74, pl. 5: 10). Much later, Krieger (1937: 457, pl. 55: 8-9) made it a variety of T. laevis. The only distinction between this variety and the nominate variety is its smaller size.
Cell dimensions: L: 45-70 µm; B: 17-20 µm; Is: c.18.5 µm; L/B: 2.8-3.7.
For the Netherlands, Coesel & Meesters (2023: 83) note for occurrence: “as in nominate variety but more markedly sub-atmophytic and less common.” It is certainly less common in the Outer Hebrides, but found in acidic habitats, especially with Sphagnum.
References:
Coesel, P.F.M. & Meesters, K.J. (2023 second edition) Desmids of the Lowlands.
De Bary, A. (1858) Untersuchungen über die Familie der Conjugaten (Zygnemeen und Desmidieen) Ein Beitrag zur physiologischen und beschreibenden Botanik.
Krieger, W. (1937) Die Desmidiaceen Europas mit Berücksichtigung der aussereuropäischen Arten. Band 13. Abteilung 1, Lieferung 3 of Dr. Rabenhorst's Kryptogamen-Flora von Deutschland, Österreich und der Schweiz.
West, W. & West, G.S. (1904) A Monograph of the British Desmidiaceae, Volume 1.