Centropyxis hirsuta  Deflandre, 1929

Diagnosis: Shell sub-hemispherical, flattened towards the anterior part. Frontal view broadly elliptical to almost circular, with eccentric, elliptical mouth, usually entire edge. The outline shows horns in varying numbers, and in addition, the dorsal part itself bears others. Side view fairly high, well rounded, sloping forward; the ventral surface invaginates quite strongly but there do not appear to be any internal chitinous flanges or flaps; the aperture appears truncated quite regularly. The horns, in the lateral view, are seen distributed over the entire shell and not located at the same height and grouped like a crown as in C. aculeata and C. discoides. Furthermore, they are similar to those of these species: hollow, sub-cylindrical, frustoconical, closed at the end by a pointed mineral particle. They are proportionally longer than in C. aculeata, commonly reaching a third of the diameter of the shell and sometimes even two-fifths. The wall is chitinoid, fairly light yellowish or yellowish brown, punctuated. There are generally no large mineral particles, but only quite abundant small particles of mud and irregular plates, which give a scabrous appearance. The dimensions are always notably smaller than those of C. aculeata and C. spinosa.

Dimensions: Diameter 72-88 µm (without horns), 108-130 µm (with horns), height about 3/5 of the diameter.

Habitat: Freshwater. France.