Phylum: Charophyta   Family: Desmidiaceae

Cosmarium hostensiense Stastny & Kouwets

Until recently known as Cosmarium variolatum var. skujae - this has proved an invaid name. Recent work by Štastný & Kouwets note: 'in our opinion the general cell morphology – including dimensions – of the present form is too much different from that of C. variolatum to merely consider it a variety of the latter (compare also Kouwets 2008). Moreover, as with C. cataractarum there is a striking difference in the ecology between both taxa and, therefore, it is proposed to classify it as a separate species'

References: 
Štastný & Kouwets (2012) New and remarkable desmids (Zygnematophyceae, Streptophyta) from Europe
Kouwets, F.A.C. (in manuscript) European Flora of the Desmid Genus Cosmarium
John, D.M. & Williamson, D.B. (2009) A Practical Guide to the Desmids of the West of Ireland