A new Rissoina species (Gastropoda: Rissoinidae) from the southeastern Pacific

We describe a new species of the genus Rissoina d’Orbigny, 1841, from the southeastern Pacific, representing the second species of this genus recorded from the continental coast of Chile. The new species was collected from coarse sand near the port of Caldera, Región de Atacama, northern Chile. The new species is distinguished from other southeastern Pacific Rissoina species by the absence of axial ribs, a characteristic brownish-caramel coloration, and a distinctive spiral microsculpture composed of very fine, regularly spaced rows of shallow, elongated, ovate–rectangular depressions separated by irregular cords. The discovery of this previously undocumented micromollusk within a relatively restricted geographic area highlights the need for further taxonomic studies on small-sized mollusks in the region, as they represent a significant component of the southeastern Pacific malacofauna.