Polycera marplatensis is a species of sea slug, a nudibranch, a shell-less marine gastropod mollusc in the family Polyceridae.

[2] This species was described from Mar del Plata, Buenos Aires, Argentina, 38°2′11″S 57°31′37″W / 38.03639°S 57.52694°W / -38.03639; -57.52694.

It has been reported from Brazil to Patagonia.

[3] Polycera marplatensis is common in the intertidal zone where it feeds on the Bryozoan Bugula sp..[3]