Genus: Test flask-shaped (Illustrated Guide, 1985).
Species: Test variable in size, about 96 μm long, 60-70 μm wide, 40 μm in thickness; frontal view pyriform, pseudostome slightly convex, dorsoventrally compressed; transparent chitinous plates arranged in series across the surface (Cash, The British Freshwater Rhizopoda and Heliozoa vol. II, 1909).
Q. symmetrica (Wallich, 1863): 90-110 μm long, 60-70 μm wide, 35-40 μm deep; test pyriform, siliceous, rectangular plates in rows; oval in cross-section; pseudopods, cylindroid (Illustrated Guide, 1985).
Quadrula symmetrica Wallich: Test pyriform, with quadrangular siliceous or calcareous paltelets (not overlapping); 80-140 μm long, 40-96 μm wide (Kudo, 1966).