Phylum: Chlorophyta Family: Desmidiaceae
Cosmarium subpunctulatum Nordstedt
Since Norstedt named this species, more recent authors have moved it to a variety of Cosmarium punctulatum. However, that species is thought to have doubtful and ill-defined credentials: see Kouwets (in manuscript). Found in moorland pools and bogs, acidic or neutral. Rather similar to other small, smooth-walled Cosmaria. Note the median inflation of large granules (but lacking a supraisthmial granule as in Cosmarium discrepans) and an L/B ratio close to 1 (0.96-1.12).
References:
Kouwets, F.A.C. (in manuscript) European Flora of the Desmid Genus Cosmarium