Shell oblong, slim, semitransparent, whorls convex and suture distinct. Last whorl occupies about 2/3 of spiral. On last whorl sculpture is made by about 20 axial little ribs vanishing at the periphery, crossed by about 10 spiral little cords not making tubercles but a close reticulum only. Apex is obtuse and it is sculptured by fine microscopical lines. Aperture is really round in form with external lip thin and without internal denticulation. Columella a little bit thickened in the lower part. Umbilicus missing. Either yellowish or uniform light brown in colour. A. punctura is a similar species but it has a different protoconch (multispiral) and a sculpture of teleconch with a closer reticulum, besides having a different distribution. Even A vermaasi is a species really similar to parvula with which, furthermore, it shares the geographical distribution. It is recognizable since it has a protoconch with a different sculpture (zigzag spiral cords), it has a different consistency of axial sculpture and due to the presence of a more developed cord placed over suture. Average measures of adult specimens reach 2 mm in height.

Habitat: it lives in the littoral zone. Common enough. Distribution: it can be found in the Straits of Gibraltar area only.