Idaliadoris neapolitana is a species of sea slug, a dorid nudibranch, a shell-less marine gastropod mollusc in the family Onchidorididae.
This species was described from Naples, Italy. It has also been reported from Numana, Ancona, Italy and the Mediterranean Sea coast of Spain.
Idaliadoris neapolitana feeds on the bryozoan Schizobrachiella sanguinea.