Desmids are unicellular, microscopic, green algae which are widely distributed in a variety of freshwater habitats, although they are typically found in clear oligotrophic water.
Taxonomically they are members the order Desmidiales with two sub-orders and numerous families. Although the cell-shape varies, they are characteristically symmetrical, often with two semicells joined by an isthmus, or ill-defined suture lines and can have a highly ornamented cell wall. Features that are important in the identification of desmids..
Over 900 species of desmids have been recorded in the British Isles but in the Outer Hebrides little is known about which species are present or their distribution. The only records on the NBN Atlas Scotland are those published by Outer Hebrides Biological Recording. The results of other surveys remain either unpublished or in the scientific literature.
This is a new project, only commenced seriously in 2019. We would like to acknowledge the considerable help given by Koos Meesters, a leading European desmidiologist, especially with sorting out errors in the early stages. Subsequently, we have received help from other European and two British workers.