Ceratosoma sinuata

Photo taken in Yap
Courtesy of Douglas Hoffman

Ceratosoma sinuata (Van Hasselt, 1824)

This has just got to be the most outrageous nudibranch on earth, and the one that wrote the book on flamboyant aposomatic coloration. Many of you still refer to this species as Miamira sinuata. The species has been recently reassigned by Valdes & Gosliner (1999) who proposed that this gorgeous beast is a member of the chromodorid genus Ceratosoma.

Because the color of animals varies greatly , this species has been the center of much discussion and numerous differences of opinion concerning whether or not there is one, two or three species represented here. On one hand I completely agree with Bill Rudman who states on the Sea Slug Forum "the number of species in the 'Miamira-group' is still not clear. Some authors, such as Baba & Hamatani (1974), consider there is a single species which ranges from the green 'sinuata' form to the purplish 'flavicostata' form. Others consider there are sufficient distinctions in external shape and colour, and radular morphology, to distinguish two or three species. While the extremes are very clear, there are many intermediate forms which suggest perhaps a continuum. At present I have placed them all as a single species, but this is through lack of knowledge rather than through some great insight."

On the other hand, I personally would prefer to separate the color forms as distinct, and given my choice I would call the critter in Doug's photo shown here, Ceratosoma magnifica. For the purpose of this Branch of the Week issue, I will bow, and refer to the group name, 'sinuata'. Hey you grad students looking for a thesis topic - this is a good one.

Because to the controversy over whose who, it is difficult to establish exactly what the range of this species is, but again I'll take the safe course and follow Bill Rudman to say it is found throughout the tropical and subtropical Indo-west Pacific.

In addition to the several submittals found on Rudman's Forum, the variation of this species can also be seen on page 93 of Suzuki's Opisthobranchs of Izu Peninsula , page 244 of Debelius' Nudibranchs and Sea Snails and page 262 of Halstead's Coral Sea Reef Guide . In these and Doug's shot you see a smooth and dramatically ridged body, with several large central nobs, the tallest just anterior to the gill plume. The foot is bright purple with yellow spots and the dorsum red with yellow lines juxtaposed to the ridges. To me, this differs greatly from the green form whose dorsal surface is tuberculate and only slightly ridged and whose color is almost uniform green with small yellow and blue spots. Even the rhinophores and gills differ in coloration between these too.

Oh well, who am I to assert that spots and stripes are different? It would have been so much easier if we just didn't know about all those darn intermediates!

Dave Behrens
Danville, Calif
Oct. 2000

Valdes, A. & Gosliner, T. (1999) Reassessment of the systematic status of Miamira Bergh, 1875 and Orodoris Bergh, 1875 (Nudibranchia; Chromodorididae) in light of phylogenetic analysis. Journal of Molluscan Studies, 65:33-45.

Douglas Hoffman and lovely wife Mieko in Micronesia.
Douglas is a successful photojournalist and video maker. He has won 15 international awards for photography and been published in American, Austrailian, Asian, Japanese, and Indonesian magazines. SDJ was the first Chinese diving magazine to publish his works. Check out the nikon 2001 calander to see one of douglas's award winning shots.

An avid diver and international award winning marine photogapher, Douglas Hoffman lives in Maui, Hawaii with his wife Mieko. The couple operates Maui Photography, and offers a range of services including wedding coordination, wedding photography, family portraits, underwater photography, stock, and assignment photography.

They also lead one or two trips a year to exciting destinations in the indo-pacific. Groups are limited to 6 - 8 people. The next trip with space is a 10 - 12 day cruise on a sailing yacht to the Burma Banks. They will depart from Phuket, Thailand in early December 2001. In August 2001, they are planning another Indonesia live-aboard trip. Check out the marine photography/indonesia link at their Web Site for additional information

For information on any of the above, send Doug email at dhimages@maui.net

Taxonomic information courtesy of Dave Behrens

David W. Behrens

Author: Pacific Coast Nudibranchs
Co-Author Coral Reef Animals of the Indo Pacific
Propriator of Sea Challengers Natural History Books !
35 Versailles Court
Danville, CA 94506
E-Mail - info@seachallengers.com
FAX - 925-736-8982
Voice Mail - 925-327-7750
Send Dave mail at seachalleng@earthlink.net

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