Pontigulasia rhumbleri Hopkinson 1919
Diagnosis: test pyriform, compressed; composed of diatom-frustules and mineral grains, bound together by an organic cement. Aperture elliptical or sub-circular without any definite neck or constriction of the test. Internal bridge ribbon-shaped, widening towards the ends, placed centrally a short distance within the aperture and attached to the broader sides of the test.
Dimensions: Hopkinson 130-140 µm; my measurements: 112-168 µm
Ecology: in Sphagnum and aquatic vegetation in shallow water.