Although widely known as Pelagella joubini, as noted on Marshall Islands Sea Slugs, I believe an earlier name for this is P. aspersa. I saw four specimens of this small nudibranch in Hawaii, one on a night dive at Makua, Oahu; two at night at Puako, Hawaii; and the figured specimen below, which was under a rock at a depth of less than 1m on the reef off Kewalo Basin, Oahu.
Created 20 April 2009
Updated 17 December 2023