Phylum: Charophyta Family: Desmidiaceae
Cosmarium luxuriosum (Kouwets) Coesel 1989
This taxon was first described as a forma of C. margaritiferum by Kouwets (1988, pp. 71-72, fig. 6: 1-5) and later raised to species level by Coesel (1989, p. 186, pl. 3: 2). It is readily distinguished by a series of large, rounded granules at the apical angles. Found in boggy moorland pools and loch-side vegetation. There are few records and is probably genuinely rare.
References:
Kouwets, F.A.C. (1988) New and noteworthy desmid zygospores from South-West France
Coesel, P.F.M. (1989) Taxonomic notes on Dutch desmids
Kouwets, F.A.C. (in manuscript) European Flora of the Desmid Genus Cosmarium