Initially reported from the Philippines, messages on the Forum report it as well from West Papua and East Timor.
A larger version of Michael Miller's photo can be found on his Slug Site. I am very grateful for his permission to use it here.
"Ceratosoma alleni was just recently described by Gosliner in the Proceedings of the California Academy of Sciences, Vol 49, No. 3, pp. 115-126, April 9, 1996. Ceratosoma alleni is named for Jerry Allen of Tucson, Arizona, who first discovered this species near Dakak Resort, Dapitan, northern Mindanao in March 1993. Thus far this species is only known from the Mindanao and Luzon Islands in the Philippines. The external morphology of Ceratosoma alleni is unique among described species of Ceratosoma. It is the only species with prolonged lateral extensions of the notum which contain glandular arrays on the ventral surface. Ceratosoma alleni closely resembles an unidentified xeniid soft coral which has been found in the same habitat. This species may closely resemble the soft coral to elude visual predators" .... Terry Gosliner [extract from Mike Miller's Slug Site]
• Gosliner, T.M. 1996. Phylogeny of Ceratosoma (Nudibranchia: Chromodorididae), with Descriptions of Two New Species. Proceedings of the Californian Academy of Science, 49(3):115-126.
Rudman, W.B., 1998 (October 2) Ceratosoma alleni Gosliner, 1996. [In] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/ceraallen
April 16, 2010
From: Anthony Wynne
Please could you help ID the nudi in the attached picture.
I have more pictures if needed.
Locality: Puerto Galera, 8 metres, Philippines, Pacific, 18 July 2008, Sandy bay. . Length: 5 inches. Photographer: Anthony (me).
email@example.com, 2010 (Apr 16) Ceratosoma alleni from Puerto Galera Philippines. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/23143
This strangely shaped nudibranch is Ceratosoma alleni
May 30, 2008
From: Brian Francisco
Concerning message #19094:
Hi Bill and Forum Readers
We believe we found Ceratosoma alleni on this morning's dive.
Along with Yung Yip's photographs from West Papua in January 2007, this expands the known range of C. alleni well beyond the Philippines.
Locality: Maubara, 10 meters, East Timor, Banda Sea, 11 May 2008, coral reef. Length: 5 cm. Photographer: Brian Francisco.
firstname.lastname@example.orgFrancisco, B., 2008 (May 30) Ceratosoma alleni from East Timor. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/21567
Considering how widepsread most tropical species of Ceratosoma are, it would have been very unusual if this species had continued to be found only in the Philippines. However, until we had actual sightings from further afield we could only guess. So your message, and Yung Yip's, are valuable contributions to our knowledge of this species.
January 5, 2007
From: Yung Yip
Photographed this specimen of Ceratosoma alleni along the south coast of West Papua (formerly Irian Jaya), Indonesia. Info on the Sea Slug forum indicate species previously found only in Philippines.
Locality: Triton Bay, near Kaimana, 30 ft, Fakfak, West Papua, Indonesia, Banda sea, 7 December 2006, White sand slope w/ small coral heads. Length: 6 inches. Photographer: Yung Yip.
email@example.comYip, Y., 2007 (Jan 5) Ceratosoma alleni from West Papua, Indonesia . [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/19094
Thanks for adding to our knowledge of this species.
June 1, 2006
From: Michael D. Miller
Concerning message #16698:
Roland Pieper of our group was able to identify a Ceratosoma alleni in a pose strongly suggestive of a solitary soft coral growth. The configuration of the foot is especially interesting in this regard. It was also found recently at Puerto Galera, in the Philippines.
Happenstance? I doubt it!
Michael D. Miller
firstname.lastname@example.orgMiller, M.D., 2006 (Jun 1) Re: Ceratosoma alleni from the Philippines. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/16747
If the gills and rhinophores weren't showing I am sure this photo could cause a few arguments about the identity of the organism.
May 26, 2006
From: Stewart L. Sy
I'd like to add another locale for Ceratosoma alleni... across the channel from Anilao. I've attached a photo. The animal was found in about 3 meters of water in front of Sabang Beach, Puerto Galera in the Philippines.
Locality: Sabang Bay, Puerto Galera, , 3 meters, Oriental Mindoro, Philippines, Pacific Ocean, 04 May 2006, sandy bottom below a floating bar. Length: 5 inches. Photographer: Stewart L. Sy.
email@example.comSy, S.L., 2006 (May 26) Ceratosoma alleni from the Philippines. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/16698
Thanks for these beautiful photos. The one alongside shows how the large tubercles can bend in the current - much like a soft coral colony. I don't want to sound greedy, but what would be very interesting would be some photos of this species - or any species of tropical Ceratosoma - feeding on a sponge. At present we know almost nothing about the biology of these animals and it would be valuable to know whether they specialise on a particular family of sponges.
May 18, 2006
From: Tristan Green
I'm new to the Forum so don't know the form, but I hope someone can help me identify this little creature.
Spotted in Anilao, Philippines at about 10 m moving across some sand between flower soft coral (Probably Xenia sp.) from memory which was almost the same colour as the nudibranch.
Locality: Anilao, 10 m, Luzon, Philippines, South China Sea, 30 April 2006, Coral reef. Length: 100 mm. Photographer: Tristan Green
I've not been able to find a photo of anything similar in any of my books.
firstname.lastname@example.orgGreen, T.A., 2006 (May 18) The soft coral mimic - Ceratosoma alleni . [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/16620
Welcome to the Forum and thanks for a spectacular first contribution. This is Ceratosoma alleni. When it was first described, the author, Terry Gosliner, mentioned its similarity to a xeniid soft coral and suggested it was probably a defensive camouflage strategy to protect it from predators. Your photos show the similarity to a soft coral with polyps retracted, very well. This animal is a member of the family Chromodorididae which contains some of the most brightly coloured nudibranchs. Most store distasteful chemicals they obtain from their sponge prey in their skin and the brightly coloured ones seem to be 'shouting loudly' to potential predators that they should be avoided. Ceratosoma alleni on the other hand, is one of the few that has decided that discretion is the better strategy, but they still store distasteful chemicals in their skin - just in case their camouflage fails.
July 21, 2004
From: Erwin Köhler
Tata, a diveguide and "brancher" at Malapascua island told me he saw Ceratosoma alleni at Gato island (close to Malapascua is., northern Cebu, Visayas) in 2003.
Erwin@Philippine-Sea-Slug.comKöhler, E., 2004 (Jul 21) Re: Ceratosoma alleni from the Philippines. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/12691
I am reluctant to include records which don't include a photo so that identification can be checked. However since this is such a distinctive animal, and seldom recorded, it seems worthwhile to include it.
March 20, 2003
From: Dave Behrens
Since it’s original collection there have been only a few sightings of Ceratosoma alleni around the Philippines. I thought I’d share these phenomenal photos taken by Constantinos Petrinos while in Aniloa, Batangas Province, Luzon, in 2002. I wish I knew if the sponge it is on is its prey species.
email@example.comBehrens, D., 2003 (Mar 20) Ceratosoma alleni from the Philippines. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/9403
October 2, 1998
From: Bill Rudman
I'm afraid we don't know much about the biology and life history of Ceratosoma alleni. Michael Miller has a good photo on his Slug Site which is where I copied the information above. Any information you can obtain during ypur studies will be of great interest to us all. I am afraid the only clue I can give you is that it will feed on a sponge.
Please keep us informed of your progress. Best wishes .... Bill Rudman.Rudman, W.B., 1998 (Oct 2). Comment on Ceratosoma alleni by Bill Rudman. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/243
September 21, 1998
From: Richard Allan Mejico
I AM A BS BIOLOGY STUDENT AT THE UNIVERSITY OF THE PHILIPPINES, DILIMAN CAMPUS. I HAVE THIS SUBJECT ON INVERTEBRATES AND MY RESEARCH TOPIC IS CERATOSOMA ALLENI. I WOULD LIKE TO HAVE MORE INFO ABOUT IT, LIKE ITS ANATOMY, ENVIRONMENT,ITS IMPORTANCE INCLUDING ECONOMIC USE AND OTHER PERTINENT INFO. I JUST NEED IT VERY BADLY AND AS SOON AS POSSIBLE. HOPING FOR FAVORABLE REPLY. THANK YOU AND HAVE A NICE DAY.
firstname.lastname@example.orgMejico, R.A., 1998 (Sep 21) Ceratosoma alleni. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/240
As Dr Rudman is away, I'll post this for others to comment on.