Shell small, turriculated formed by eight flattened teleoconch whorls. Sculpture of three spiral keels per whorl, with the interspaces bearing clearly defined axial raised lines. The top whorls are helicoid and quite sunken into the next teleoconch whorl, with which they form an angle of about 90°. Columellar tooth faint or wanting.
common size :
up to 4.0 mm.
This species is almost impossible to confuse with other Mediterranean species. A slight resemblance could be observed with the turriculate and spirally sculptured shell of Seila trilineata (Philippi, 1836), but the latter is bigger, and does not have an heterostrophic apex. The most likely confusion is with another immigrant, Oscilla jocosa Melvill, 1904, which is distinguished by a smaller size, larger body whorl in relation to the spire, and spiral keels less acute and somewhat beaded, not smooth as in the present species. The lack of tooth stressed by van Aartsen (1994) is not applicable as a key, as there are specimens like the one figured herein with a distinct tooth.
BIOLOGY / ECOLOGY
Pyramidellidae are ectoparasites, mainly of sedentary polychaetes and molluscs.