Okenia impexa is a species of sea slug, specifically a dorid nudibranch, a marine gastropod mollusc in the family Goniodorididae.
This species was described from Brazil. It is known from Brazil north to North Carolina, USA. It has also been reported from the western Mediterranean and the Cape Verde Islands.
This Okenia has a tall body and about five or six lateral papillae on each side of the mantle.
The maximum recorded body length is 3âÂÂ4 mm or up to 7 mm.
Minimum recorded depth is 0 m. Maximum recorded depth is 0 m.
The diet of this species is unknown but the shape of the animal resembles ascidian eating species of Okenia such as Okenia aspersa.