Like other species of the genus, its cells have a neck and a wide aperture to a canal that hosts a single flagellum and its feeding apparatus.

[2] Members of the genus Urceolus are distinguished by the presence of a 'neck' at the anterior end of their oval-shaped cell, followed by a wide aperture or 'mouth' into a deep canal where the feeding groove and the flagellum originate.

[1] In particular, U. cyclostomus is distinguished from other species of the genus by its more or less rigid and regular body shape, a less developed 'ingestive organelle' or feeding apparatus, and a more conspicuous 'hatching' (i.e. more pronounced stripes) of the pellicle.

It has been recorded in bogs of the Central Russian forest-steppe region[2] and numerous ponds in the Czech Republic, where it feeds on epipelic cyanobacteria and other kinds of algae.

[1] Later, Russian biologist Konstantin Mereschkowsky compared Stein's illustrations of P. cyclostomum with the description of his own genus and species, Urceolus alenizini, which he published the previous year in 1877.