Cosmarium druimnahimrichense C.D.N. Johnson spec. nov.

Cosmarium druimnahimrichense is currently only known from Loch Druim na h-Imrich, near Loch a’ Charnain, South Uist, Outer Hebrides (also known as the Western Isles; see figure 1 for geographical position west of the Scottish mainland). In size and morphology, there are some similarities with C. subspeciosum Nordstedt 1875, however that species only has one pyrenoid per semicell and other differences noted below. Other taxa with some similarities are discussed but no taxa were found to suggest a close relationship. Therefore, a new name has been chosen to avoid further taxonomic confusion.