This pretty little chromodorid was named originally from La Jolla, California, by Theordore Dru Allison Cockerell in honor of his wife Wilmatte Porter Cockerell.
Since then this species has been reported from Monterey, California, to Isla Cedros and Bahia Tortugas, midway down the Baja California peninsula. Its has been reported both intertidally and subtidally, to a depth of about 20m. It may feed on the sponge Dysidea amblia. The radular formula varies from 38-68 rows, with 23-36 teeth in half row. There is no rachidian tooth.
The body color is an "ultramarine blue," with darker blue rhinophores. A central light blue stripe runs from between the rhinophores to the gills; the dorsum is margined with a thin white line. Most striking are the two yellow longitudinal stripes (staring at the side of each rhinophore, continuing posteriorly to behind the gills where they join); the yellow may also form an arc across the front of the rhinophores. Dave Behren's Pacific Coast Nudibranchs (1991) illustrates a specimen without the arc, whereas MacFarland's (1966) drawing shows the arc. There are 9-11 branchial plumes, and 12-14 leaves on each rhinophore. Maximum length is about 34 mm.
Imperial Beach, CA 91932