Phylum: Charophyta   Family: Desmidiaceae

Cosmarium pankakoskiiforme C.D.N. Johnson 2024

First described and illustrated by Johnson (2024: 5, fig. 1) with a drawing by Frans Kouwets (fig. 2).
Cells small to medium sized, marginally longer than broad. Semicells sub-semicircular in outline, deeply constricted; sinus with a thickened-wall at the apex, sinuous margins, open showing an elongate-ovoid opening. Semicell a slightly broadened semicircle, basal angles rounded with yellowish thickening, also a little protracted. Thickening at the basal angles consisting of two papillae in juxtaposition, best seen in side view. Apex broadly rounded; cell wall in face-view faintly undulate, caused by mucus pores. Apical view rhomboid with side thickening, lateral view circular. Chloroplast axile with two central pyrenoid. Zygospore unknown.
Cell dimensions: L: 31-37 µm; B: 31-34.5 µm; Is: 10-12.7 µm; Th: 14-18.5µm; L/B: 1.05-1.08.
C. pankakoskiiforme is currently only known from Loch na Gearrachan, Claddach, North Uist. Found in shallow water with a gravelly substrate comprising subglacial moraine deposition, consisting of Lewisian gneiss.
Complete taxonomic description: Cosmarium pankakoskiiforme.

References: 
Johnson, C.D.N. (2024). Description of a new desmid species, Cosmarium pankakoskiiforme, from the Outer Hebrides, Scotland, UK. Desmidiological Communications 12.