Plagiopyxis penardi Bonnet & Thomas, 1955

Diagnosis: Shell transparent, clear, or slightly yellowish, circular or slightly oblong in ventral view. Pseudostome faintly visible and detected by a double-contoured line crossing the width of the theca in the upper third, sometimes entirely invisible. Discreet, highly transparent, exogenous cover consisting of amorphous mineral plates. In lateral view, the dorsal membrane returns to a very low visor on the ventral face: this ventral face, after having followed an almost straight course (starting from the base), bends abruptly into a curve in the arc of a circle penetrating at inside, then comes to complete its course a short distance from the stop of the membrane forming a visor, leaving a narrow crack at their meeting point.

Dimensions: Length 73-84 (96) µm; approximately equal thickness and not exceeding half the diameter.

Ecology: Soil. In the organic mucus covering dead leaves, rotting in marottes in the forest; in acid humus, resulting from the transformation of dead leaves into a humid environment (dense undergrowth). France.