Phenacolepas: Round or oval limpets; apex posteriorly recurved; sculpture of radial ribs or cords and concentric striae; operculum lacking.

This genus contains several extant species that are characterized by a large (> 8 mm), conical or cap-shaped shell. The ventral side of the shell has a row of denticles on a slightly raised keel along the apertural rim, although this feature is lacking in Plesiothyreus cinnamomeus and its junior synonym Plesiothyreus pulchellus (Lischke, 1871). Masculine.

Shell capuliform, apex generally near the posterior border, but can overhang the border or can be situated in the middle of the shell; the radials are stronger, even strong, or less strong than the concentric ridges. They can be con¬stituted by knots, individual knobbles or spines or can be completely unexistent. Can have inside, on the posterior border, a well marked septum, denticulated or not. Tertiary - Recent.