Quinnia ionica is a species of sea snail, a marine gastropod mollusk in the family Seguenziidae.

The carina is margined below by a broad, shallow, round furrow, which is defined on its inner side by a sharp spiral thread.

Angulated above, tumid on the base, where (unlike Carenzia carinata (Jeffreys, 1877)) the edge of the umbilicus is the most projecting part.

The columellar margin is patulous, a little reverted, scarcely twisted, with a broad deep sinus above, a strong, but not sharp, twisted tooth projecting at about three-fourths of its length, below which is a smaller sinus running out into a point at the extreme end of the columella.

Within the umbilicus is a strongish undefined spiral furrow answering to the columellar tooth, and the lines of growth are strongly defined.