Western Pacific from Japan to eastern Australia. Mediterranean.
Tukang Besi Archipelago, SE Sulawesi, Indonesia, 12m deep, 25 September 1999. UPPER: 6 mm long, Photo: Lindsay Warren. LOWER: Cannes, France -Mediterranean Sea. Photo: Jean Lou Ferreti
Originally described from the Naples, the Mediterranean species has been identified with this animal from the western Pacific. It is a strange distribution and the identity needs further investigation. The enrolled rhinophores and blade-shaped radular teeth place it in the genus Placida.
• Baba, K. (1959) The family Stiligeridae from Japan (Opisthobranchia- Sacoglossa). Publications of the Seto Marine Biological Laboratory, 7: 327-334.
• 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.
Rudman, W.B., 2000 (February 25) Placida cremoniana (Trinchese, 1893). [In] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/stilcrem
March 29, 2010
From: Cynthia Trowbridge
Concerning message #11425:
The distribution and diet of this species is intriguing (based on all the messages). I wanted to mention that the Hiranos, their research students, and I recently published a paper on the 11 species of Okinawan sacoglossans that eat Derbesia (Placida cremoniana), Bryopsis (many), and Codium (many). Electronic e-prints are available from me.
- Trowbridge et al. (2010). Subtropical sacoglossans in Okinawa--at "special risk" or "predictably rare"? Amer. Malac. Bull. 28: 167-181.
Also, after about 26 years with Oregon State University (graduate student, 2 post-docs, instructor, and senior research associate), I am now associated with Oregon Institute of Marine Biology (Univ. Oregon). My institutional e-mail is email@example.com and my personal e-mail is firstname.lastname@example.org
Thanks for all your hard work with the Sea Slug Forum!
email@example.comTrowbridge, C.D., 2010 (Mar 29) Re: Algal food of Placida cremoniana. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/23409
I look forward to seeing a copy
April 1, 2008
From: Mikel Cortes
I found this sacoglossan last October, it is the first time I ever have seen one of them. Is it Placida cremoniana? I took the photo at 20 metres, inside the Bilbao harbour in the Bay of Biscay, North of Spain.
Locality: Bilbao, inside the harbour., 20 metres, Sapin, Bay of Biscay, 21 October 2007. Length: about 10 mm. Photographer: Mikel Cortes.
firstname.lastname@example.orgCortes, M., 2008 (Apr 1) Placida cremoniana from the Bay of Biscay. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/20997
Yes this is Placida cremoniana. This species has a very strange distribution. It was described by Trinchese (1893) from the Mediterranean and then Baba (1949) reported it from Japan. Since then it has been found at various other places in the western Pacific as far south as Sydney in eastern Australia. We should really compare the anatomy of Mediterranean and Pacific animals to confirm they are the same species. Like a number of animals with puzzling distributions like this we can't say if its original home is the Mediterranean just because it was reported there first. Perhaps it hitched a ride to Europe on the bottom of some early explorers sailing ship?
September 16, 2005
From: Sascha Schulz
I found this in a Wollongong rockpool.
Locality: Wollongong, NSW, southeastern Australia, rockpool. About 15 mm long, initally under a rock which was kicked over. May 2005
Is it a Flabellina?
email@example.comSchulz, S., 2005 (Sep 16) Placida cremoniana from Wollongong, NSW, Australia. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/14757
Although this looks superficially like an aeolid, it is a sacoglossan, much more closely related to Elysia than to Flabellina. This species appears to be identical to the Mediterranean Placida cremoniana. As it is found in many parts of the Indo-West Pacific, this strange distribution is either very ancient, or the result of shipping in the last 200 years.
November 18, 2003
From: Cynthia Trowbridge
PHOTOS: Upper - Bryopsis sp.. Lower - Derbesia showing sporangia.
Dear Bill and colleagues,
I have recently returned from working in Okinawa with Yoshi and Yayoi Hirano and their graduate students. On this visit (Nov 2003) to the west coast of the main island of Okinawa, we were able to clear up numerous mysteries of algal hosts of sacoglossan species. In this message, I describe the diet of Placida cremoniana.
All 3 specimens that we found were on Derbesia which was very common on shady overhangs on shallow subtidal rocky platforms (<1 m). With 10 Bryopsis spp., 2 Derbesia spp., and 2 Pedobesia spp. on Japanese shores, there are many small green algae that could be sacoglossan hosts. In addition to collecting the slugs on Derbesia, we confirmed in lab experiments that Derbesia is actually an algal host (i.e., slugs ate algae, slugs grew, and algae was damaged).
How do you tell these potential algal host genera apart? Bryopsis usually has a main axis with short lateral branches; it looks similar to a feather (see photo). If the alga has no internal cross walls (no cells) and does not branch like a feather, you need to look at the reproductive structures.
On Derbesia, the algal filaments have round to oval structures attached to their surface (see photos). These are the sporangia (spore-bearing structures). If these are present, you need to see if there is there is a basal wall plug present. If it is present (as in these photos), then the alga is Derbesia; if the plug is absent, then you probably have Pedobesia. Many sacoglossans eat Pedobesia lamourouxii (formerly known as Derbesia lamourouxii) so sacoglossan researchers need to find reproductive hosts to confirm the algal genus.
My photos were taken with a portable Olympus Mic-D digital microscope that plugs into a USB port of a computer.
Trowbridge, C., 2003 (Nov 18) Algal food of Placida cremoniana. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/11425
I look forward to hearing more of your work with Yoshi and Yayoi Hirano,
August 4, 2003
From: Marina Poddubetskaia
Here is a shot of Placida cremoniana from Mediterranean. In the message from Thierry Thibaut you said it could feed on filamentous algae. In Cerbere I found 4 specimens of this species and all of them were on this kind of algae (see the lower photos) which is very common in Cerbere. Unfortunately, I wasn't able to photograph this tiny species on this algae because of the movement in the water. So, I had to move it to the less turbulent place.
Date: July 08, 2003
Location: Cerbere, France, Mediterranean coast
Site: Les 3 moines
Photos: Marina Poddubetskaia - Nembro website
Poddubetskaia, M., 2003 (Aug 4) Placida cremoniana from Cerbere. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/10632
Perhaps someone can identify the algae for us
March 15, 2002
From: Akos Lumnitzer
On a night dive in October 2001 at Oak Park in southern Sydney, my wife found these two tiny slugs. They remind me of Ercolania cf. boodleae looking at the shape, but the colour seems reversed. They were about 5mm long.
Akos.Lumnitzer@exel.comLumnitzer, A., 2002 (Mar 15) Is this a species of Stiliger?. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/6410
I think they are Stiliger cremoniana. There is a possibility they are Favorinus tsuruganus but I can't see enough detail to decide whether they are a sacoglossan or an aeolid.
August 28, 2001
From: Nishina Masayoshi
Here are photos of a beautiful animal. In all the photos of Placida cremoniana that I have seen, the body and and cerata are yellow or light brown.
But this animal is much redder or orange. With the naked eye, it looked red. It had crawled on the stone top like a photos.
Date: 12 Aug 2001
Location: Echizen beach, Japan
Frequency in Echizen: rare
Yes this is Placida cremoniana. Your animal is a brighter orange than I have usually seen and the white mark on the rhinophores is more obvious, but I am sure it is within the normal range of colour variation of the species.
May 12, 2001
From: Thierry Thibaut
Hello everybody, a friend of mine, Jean Lou Ferreti, took this picture in front of Cannes (Mediterranean Sea - France) on Padina pavonica. Does anybody knows which species it is ?
Thank You Very much
firstname.lastname@example.orgThibaut, T., 2001 (May 12) Placida cremoniana from Mediterranean. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/4305
This is the sacoglossan Placida cremoniana. Although it was found on Pavona I suspect it is feeding on the hair-like filamentous algae in the photo. This species was first described from the Mediterranean but it seems to have a wide Indo-West Pacific distribution as well.
Thanks agan for the interesting photo,
May 12, 2001
From: Bill Rudman
To accompany Thierry Thibaut's message about Placida cremoniana from the Mediterranean, here are some photos of an animal from Sydney, NSW, Australia, which seems externally to be identical. It is sometimes quite common intertidally in tangled mats of filamentous green algae. Previously on the Forum I have called it Stiliger cremoniana. Externally Stiliger and Placida differ in whether the rhinophores are simple (Stiliger) or enrolled (Placida). From the photo (Lower left)you can see that the rhinophores are enrolled so it seems that this species is found in both the Mediterranean and the Indo-West Pacific. Although it was first described from the Mediterranean it does not necessarily mean it originated there. It is just as likely it travelled there on the bottom of a sailing ship as vice versa. In New South Wales I have records from Sydney south to Eden.
PHOTOS: Long Reef, Sydney, intertidal April 1985. Many specimens on filamentous green algae 12-20mm long. Lower Left: Head and rhinophores. Lower Right: Showing diverticula in cerata. PHOTOS: Bill Rudman
Rudman, W.B., 2001 (May 12) Placida cremoniana from New South Wales. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/4321
May 12, 2001
From: Kathe Jensen
I am pretty sure that Placida is the correct genus for Placida cremoniana. It has a penial stylet and blade-shaped radular teeth according to Schmekel & Portmann (1982). I have never seen the beast alive. Also, I am not sure that what has been called Placida (or Hermaea) cremoniana outside the Mediterranean (e.g. Japan and Australia) is actually the same species. We need more detailed studies of reproductive systems.
email@example.comJensen, K., 2001 (May 12) Re: Placida cremoniana. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/4325
I checked Trinchese who also describes blade-shaped teeth. I must say that until I saw Thierry's photo of a Mediterranean specimen I had my doubts about the identity of specimens from the Pacific. I agree that we need to look at the anatomy of these animals. However the colour and shape seem to be identical.
February 27, 2000
From: Lindsay Warren
These two beautiful specimens which we believe to be a species of Stiliger were found by Krzys Berkieta at about 10.30am on 25 September 1999 at a depth of 12 m on filamentous algae growing on plastic fronds suspended beneath a rompong (fish attracting device) anchored off shore in several hundred meters of water near Pulau Kaledupa [Tukang Besi Archipelago, SE Sulawesi, Indonesia - Operation Wallacea]. Size: UPPER: 6 mm, LOWER: 4 mm.
The base colour of the body is dull translucent orange. The bottom half of the many cerata are the same dull translucent orange but are also sprinkled with gold specks which sparkle, the top half of the cerata are solid black. The rhinophores and upper part of the head are black. The area around the eye spots located beneath the rhinophores on either side is dull orange and the mouth parts orange. Down the notum between the cerata is a raised ridge dusted with black. Photos: Lindsay Warren.
Is this a new one or has it already been described?
All the best
firstname.lastname@example.orgWarren, L., 2000 (Feb 27) Stiliger cremoniana from SE Sulawesi. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/1956
This animal is found at least in the western Pacific from Japan to eastern Australia. It was identified with Stiliger cremoniana Trinchese 1893 from the Mediterranean by Baba (1949) but to my knowledge I don't think any further attempt has been made to compare the Mediterranean and Pacific animals. In colour they are indeed very similar.