Phylum: Charophyta   Family: Desmidiaceae

Cosmarium bipyrenoideum P.F.M. Coesel & K.J. Meesters 2015

First described in 2015 from a shallow pool in ‘Kuinderbos’ near Kuinre, The Netherlands. The specific epithet describes it well as few cells of this size have two pyrenoids per semicell.
Single cell dimensions: L: 42.6 µm, B: 32.3 µm, Is: 13.3 µm; L/B:1.32.
The current find is from the shallow margins of a disused quarry which is slightly alkaline. This is a first and only British record. A seemingly rare desmid.

References: 
Coesel, P.F.M. & Meesters, K.J. (2023 second edition). Desmids of the Lowlands.
Kouwets, F.A.C. (2025). European Flora of the Desmid Genus Cosmarium.