Shell cylindrical, very small, with heterostrophic topwhorl of "type C" (according to van Aartsen, 1987). The three flattened whorls have a sculpture consisting only in well marked and oblique spiral keels. A well marked tooth is present in the columella. No umbilicus is present.
common size :
1.4 mm in length.
H. cylindrica resembles O. jocosa in shell morphology, particularly for the well marked spiral keels that cover the whole shell. But the former has a more ovate shell, less whorls and the keels are more than three and not equal in thickness. Moreover, O. jocosa has a topwhorl of "type B" and is bigger in size.
BIOLOGY / ECOLOGY
Pyramidellids are ectoparasites, mainly of sedentary polychaetes and molluscs.
the Mediterranean records and East African materials seem to indicate that this is a shallow-water species.