Teleoconch: with microscopic axial threads in interspaces between spiral and/or axial ribs or lirae; columella with a more or less prominent angulation at the inner end of the anterior channel.
Head-foot: left (anterior) pallial tentacle simple. Internal anatomy (examined species: Stosicia annulata and S. mirabilis) : hypobranchial gland very thick, apparently secreting large amounts of deep pinky mucus (in the shape of elongate, narrow ribbons Anterior chamber of stomach (sub)equal in length to posterior chamber. Rectum in Stosicia mirabilis sack-shaped, containing regularly packed fecal pellets. Male with copulatory organ very complex. Female with seminal receptacle at left side of bursa copulatrix (only examined in Stosicia annulata).
Radula : central tooth with one pair of basal denticles ; outer marginal teeth with the outer margin smooth.
Operculum: thin, simple.

Shell, oval-conic with cancellate sculpture. Aperture, semicircular to ovate; outer lip variced and fimbriated. Anterior canal, deep cut, visible from bottom as the Planaxis shells. Operculum, not pegged inside but pointed with a terminal nucleus. This group of shells is closer to the Family Planaxis but it is put under Rissoidae traditionally.

The genus Stosicia is very distinctive from both Rissoina s.l. and Zebina s.l. in the anterior channel being more or less notched and in having microscopic axial threads in the interspaces between the spiral ribs. In the type species, Rissoa planaxoides, the axial threads are only visible on the last whorl of the teleoconch. Both the simple operculum and the location of the sperm receptacle at the right side of the bursa copulatrix suggest a closer relationship to Zebina s.l. than to Rissoina s.l.

Tropical Indo-Pacific and Western Atlantic.