Opisthobranch of the Week Data
Gymnodoris rubropapillosa is considered to be common on Okinawa, but only at a single collection site. All observed and collected individuals were seen beneath Tengan Pier amid silty-sand and strewn oyster shell rubble. The great majority of the animals were found crawling on top of the substrate; a few were seen crawling on the vertical concrete pilings within a meter of the bottom. During a dive on 4 May, 1996, I observed 16 of these attractive gymnodorids! I frequently see 15-25 species of opisthobranchs in the general "under-pier" area, but only infrequently do I see other gymnodorids. Possibly the great numbers of opisthobranchs found at this locality are due to the dense colonies of bryozoans, cnidarians, poriferans, and others, covering the pier pilings and other associated pier structures. It should perhaps be pointed out that I frequently exceed 200 minutes of dive time, which may, at least in part, explain the high numbers of 'branchs seen here.
The only other Gymnodoris found here that resembles G. rubropapillosa is G. ceylonica, of which I have collected only a single individual.