Diagnosis: shell ovoid, compressed; aperture with a short collar, one lip slightly longer than the other one; shell composed of oval siliceous scales, being smaller close to the aperture; apertural scales not denticulated; nucleus relatively large, finely granular with centric or eccentric nucleolus; filopodia.
Dimensions: Length 50-68 µm, nucleus c. 10 µm (n=2).
Ecology: In sphagnum (Tirol, Austria) and sediments of a small stream (the Netherlands).
Remarks: This is a larger species than the one described by Penard. It differs from T. pulchellum by its larger size and the structure of the nucleus.