Phylum: Charophyta   Family: Desmidiaceae

Cosmocladium pulchellum Brébisson

Brébisson's original description describes the cells as being attached by twin filamentous threads in a tree-like formation and attached to a substrate such as an alga. Prescott (2001) sticks vehemently to Brebisson's original diagnosis but presents a stylised image that doesn't reflect the dimensions given, especially in terms of the isthmus. Later authors, includings the Wests & Carter (1923), offer a different view. The Wests & Carter note: "Colonies usually small, rarely consisting of more than 8 cells, only very slightly or not at all branched, free-floating; cells mostly with their broad surface perpendicular to the direction of the connecting gelatinous threads; colonies sometimes enveloped in a very thin, scarcely visible mucus." A rare species: interestingly, the Wests specifically mention Harris in the Outer Hebrides as a site.

References: 
West, W., West, G.S. & Carter, N. (1923) A Monograph of the British Desmidiaceae, Volume 5
Prescott, W.G., et al. (2001 reprint) A Synopsis of North American Desmids. Part II, Desmidiaceae: Placodermae, Section 3
Kouwets, F.A.C. (1999) A check-list of desmids (Chlorophyta, Zygnemaphyceae) of France