Okenia mexicorum is a species of sea slug, specifically a dorid nudibranch, a marine gastropod mollusc in the family Goniodorididae.
This species was described from Jalisco, Mexico, and it is known to occur further north, as far as Baja California Sur.
[2] This Okenia has a narrow body and eight to ten pairs of short lateral papillae.
There is a median ridge on the back, from which a single papilla arises just in front of the gills.
The body is translucent white and the mantle is covered with opaque white pigment.