Phylum: Charophyta   Family: Desmidiaceae

Cosmarium klebsii Gutwinski 1892

Semicells are subpyramidal with broadly rounded basal angles and a truncate apex. The sinus is dilated at the apex then closed for two-thirds of the length. The smooth wall is covered in fairly large mucus pores, which are randomly spread. There is a supraisthmial row, which seems a consistent feature. The distribution is unclear as it has been confused with other species in the past.

References: 
Kouwets, F.A.C. (in manuscript) European Flora of the Desmid Genus Cosmarium
Coesel, P.F.M. & Meesters, K.J. (2007) Mesotaeniaceae and Desmidiaceae of the European Lowlands
West, W. & West, G.S. (1905) A Monograph of the British Desmidiaceae, Volume 2