Phylum: Charophyta   Family: Desmidiaceae

Cosmarium neocrenatum M.C. van Westen & P.F.M. Coesel 2021

It has much in common with the confused species complex of Cosmarium crenatum Ralfs 1848. When Ralfs described this species, he made no mention of central ornamentation. Later authors have broadened the original concept inducing the current authors to describe these broader forms as a separate species. The central ornamentation can be quite ephemeral, and deep focus is often needed to see it. The few Outer Hebridean samples show 5-6 supraisthmial granules and up to five elongated warts.
Cell dimensions: L: 33.6-35.3 µm; B: 29-30.6 µm; Is: 14.2-14.6; Th: 18.4-19.7 µm; L/B: 1.12-1.19.
A scarce desmid. The only samples from the Outer Hebrides have come from moss on wet rocks.

References: 
Kouwets, F.A.C. (2025). European Flora of the Desmid Genus Cosmarium. Part 1: Text. Part 2: Plates.
Van Westen, M.C. & Coesel, P.F.M. (2021). Taxonomic notes on desmids from the Netherlands IV, with a description of another five new species.