Phylum: Charophyta   Family: Desmidiaceae

Xanthidium laeve (W. Schmidle) P.F.M. Coesel & K.J. Meesters 2023

First described and illustrated by Schmidle (1893: 94, pl. 4: 7). Recently, Coesel & Meesters (2023: 195) raised it to species level. The main feature is the wide-open sinus and rounded basal angles. The spines are relatively short and stout.
Cell dimensions: L: 62-90 µm; B: 51-80 µm; Is: 17-23 µm; Sp: 13-16 µm; Overall LxB: 75-100 x 70-105 µm.
An infrequently recorded species, found in variously acidic waters such as loch-margins and moorland pools, also with Sphagnum.

References: 
Coesel, P.F.M. & Meesters, K.J. (2023 second edition). Desmids of the Lowlands.
Schmidle, W. (1893). Beiträge zur Algenflora des Schwartzwaldes und der Rheinebene.
Van Westen, M. (2024). Sieralgen in Drenthe.