Aldisa smaragdina is a species of sea slug, a dorid nudibranch, a marine gastropod mollusk in the family Cadlinidae.

It has subsequently been reported from the Atlantic coast of Spain and from Portugal.

[3] This species has raised rounded tubercles covering the dorsum.

There are two round markings on the back which are darker in colour.

The two darker round markings on the back of the animal closely resemble the inhalant pore sieves of Phorbas, providing excellent camouflage.