P. rhumbleri, right: 126 µm
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.
Pontigulasia rhumbleri, with aperture and bridge, shell 112 µm -Tirol, Austria
Pontigulasia rhumbleri, with bridge (right), shell 120 µm -Tirol, Austria
Both arrows indicate the network structure of the organic cement
Bridge inside the test, as seen through the aperture
Pontigulasia rhumbleri, bridge