Shell with five flattened whorls, and a sculpture consisting in three well marked spiral cords and faint growth lines. The spiral cords are rounded and somewhat beaded, especially the adapical one. A clear tooth is visible on the columella. The protoconch is making an angle of 135° with the teleoconch axis.
common size :
2.5 mm in length.
As was the case of Cingulina isseli (Tryon, 1886), this species cannot be confused with any other Mediterranean pyramidellid, due to the turriculated shell, sculpture of spiral keels and a typical marked tooth on the columella. For these characters, O. jocosa is quite similar to C. isseli, from which is nevertheless distinguishable by the smaller size, less turiculated shape, more rounded, somewhat beaded spiral cords and by the different top whorls (rather planorbid in O. jocosa, but helicoid in C. isseli). Moreover the columella of O. jocosa has a marked tooth, while the columella of C. isseli is smooth. Yet, Seila trilineata (Philippi, 1836), a Mediterranean cerithiopsid, may show a shell shape very similar to that of O. jocosa, but lacks, of course, an heterostrophic apex and any columellar tooth.
BIOLOGY / ECOLOGY
Pyramidellids are ectoparasites, mainly of sedentary polychaetes and molluscs.