[1] It was first described by the phycologist Gilbert Morgan Smith in 1918, with Planktosphaeria gelatinosa as its type species.

Often, Planktosphaeria forms loose ring-like aggregations shortly after vegetative reproduction; when this happens, the mother cell wall may remain, which is a useful identification trait.

[3] The taxonomy of Planktosphaeria has been muddled in confusion, particularly with regards to the similar genus Follicularia.

[4] Follicularia is a genus that produces zoospores, while Planktosphaeria was characterized by reproduction via autospores only.

[4] Phylogenetic analysis of the strains isolated by Starr has revealed that zoospore-producing "Planktosphaeria" species were separate from autospore-producing algae, and therefore the name Follicularia has been reapplied to zoospore-producing algal strains.