Phylum: Charophyta Family: Desmidiaceae
Cosmarium speciosum var. simplex Nordstedt
C. speciosum is a species complex with a broad size-range. Variety simplex was named for the simple granules (as opposed to var. biforme with emarginate granules). However, intermediate forms have been found confusing the situation. I'm grateful to Frans Kouwets for confirming my Haclait and Ardivachar finds.
Kouwets, F.A.C. (in manuscript) European Flora of the Desmid Genus Cosmarium
Prescott, W.G., et al. (2001 reprint) A Synopsis of North American Desmids. Part II, Desmidiaceae: Placodermae, Section 3