Valves clavate, swollen at the center of the valve. Length: 20–36 μm, breadth: 9.3–11.3 μm. Headpole is broadly rounded, capitate and footpole is narrow. Axial area is narrow. Central area small, rectangular. A stigma is present in the central area close to the proximal raphe endings. Striae punctate, distinctly radiate, 10–14 in 10 μm. SEM: striae composed of biseriate or biseriate turning to uniseriate striae, the areolae with volate occlusions giving the areolae C - or S - shaped openings. Areolae bordering the axial area C-shaped, with the closed side of the C facing the axial area. Raphe undulate, with proximal ends dilated. Stigmal opening small, round (Figs 289–290). Distal raphe end deflected onto the mantle (Figs 291–293). Apical pore fields with a few porelli on the valve face, extending onto the mantle. Pore fields are bisected by the distal raphe end. Porelli are physically and structural differentiated from the areolae (Fig. 292).

Observations: —The population considered here appears to be closely related to G. truncatum Ehrenberg sensu Reichardt (2001) by having biseriate striae evident in SEM. They differ, however, by the population from Lake Baikal having smaller and more elongate valves.