Difflugia cylindrus (Thomas, 1953) Ogden, 1983

Diagnosis: Shell usually opaque, cylindrical, tapering evenly from the aboral region to the aperture, composed mainly or medium to large pieces or quartz with the occasional diatom frustule on the rough surface, but the latter are seldom incorporated into the thick structure; aperture irregular in both outline and composition, being roughly circular and usually surrounded by small particles but often incorporating medium particles that produce a jagged margin.
Ultrastructure: small areas of organic cement in the form or a network are seen infrequently; each mesh of the network is between 300-500 nm in diameter, has thick walls and is covered by a thin perforated layer of cement, the pores or which are evenly distributed and are about 30 nm in diameter.

Dimensions: Thomas (1953): Shell length 220-260 µm; width 70-90 µm; aperture 40-44 µm. Ogden (1983): Length 186-264 µm. My measurements: Length 207-255 µm.

Ecology: Freshwater, sediments. I found several living specimens in a sample from the Haaksbergerveen, the Netherlands.