Placida cremoniana (Trinchese, 1893)
This species was originally described from the Mediterranean near Naples. It is one of several that have been found to occur in the Indo-Pacific as well. Bill Rudman points out "Although it was first described from the Mediterranean it does not necessarily mean it originated there. It is just as likely it traveled there on the bottom of a sailing ship or vice versa."
Looking very much like an aeolid nudibranch, the rolled rhinophores give away it's true identity as a sacoglossid. Most sacoglossids feed on algae and are green in color from incorporation of the alga's chloroplasts into their own tissue. This species, while it does feed on filamentous algae, does not take on its color. Some specimens have a line comprised of white specks on the rhinophores.
A series of photos from Japan can be viewed at Placida cremoniana . Bob Boland's Okinawa Sea Slugs site also has a great photo taken by Atsushi Ono. There are also photos in Opisthobranchs of Bali and Indonesia page 45, Opisthobranchs of Izu Peninsula on page 37, and Opisthobranchs of Kerama Islands page 43.
Globally the species has been documented from the French Mediterranean Sea; Echizen Beach, Japan; Zamami Island, Kerama Islands, Okinawa; Tukang Besi Archipelago, SE Sulawesi, Indonesia ; (Mike's specimen here) Sydney south to Eden in New South Wales, Australia and Cabo Plumo, Baja California, Mexico. Like most sacoglossids it is tiny, measuring up to about 6-7 mm in length.
Angulo-Campillo,o. 2002. New distributional records for opisthobranch mollusks
from the Golfo de California, Mexico. The Festivus. 14(10):117-122
Ono, Atsushi. 1999. Opisthobranchs of Kerama Islands. Hankyu Communications, Japan. 183 pp.
Susuki, K. 2000. Opisthobranchs of Izu Peninsula. Hankyu Communications, Japan. 178 pp.
Tonozuka, T. 2003. Opisthobranchs of Bali and Indonesia. Hankyu Communications, Japan. 165 pp.
Trinchese, S. 1893. Nuovi Ascoglossi del golfo di Napoli. Rendiconti dell'Accademia delle Scienze Fisiche e Matematiche della Societa di Napoli, 2(7): 154.
Trinchese, S. 1896. Ricerche Anotomiche sulla Hermaea cremoniana (Tr.). Memorie della Classe di scienze fisiche, matematiche e naturali, Serie 5, 6: 35-45.
WEBMASTER'S NOTES: As with the previous week's selection, This photo was taken with a housed Olympus 750 UZ in supermacro mode with a 5400 K video light. Although the photo itself again is nothing to write home about, it does illustrate the ability of the 750 UZ to function in area of extreme or super macro. Animal was in the range of 5 to 7 mm. The video light had to be used as the Olympus 750 cannot function with a slave strobe in the super macro mode. If anybody from Olympus is reading this, this ability would be a welcome addition in the next version.
David W. Behrens
Pacific Coast Nudibranchs
Send Dave mail at firstname.lastname@example.org