Difflugia yorkui Nicholls, 2007
Diagnosis: test large, covered with large and irregularly shaped siliceous particles except in the anterior region where particles are very small; test roughly circular (not compressed) in transverse cross-section, tapering towards both anterior and posterior ends from its widest point at about the middle of the test. Aperture relatively small and circular, (50-63 µm in diameter. Organic basal material of the test (cement) organized in an open-meshed pattern of pores 0.3-0.8 µm in diameter separated by ribs 0.2-0.4 µm in width. Living cells or cysts not observed.
Dimensions: Nicholls: 305-370 µm long and 140-162 µm wide; my measurements 280 µm.
Ecology: fresh water; Canada, the Netherlands (Naardermeer).
Remarks: the test resembles an elongated rugby-ball.