Elysia atroviridis
Baba, 1955
Order: SACOGLOSSA
Superfamily: ELYSIOIDEA
Family: Elysiidae
DISTRIBUTION
Japan (except Hokkaido, Okinawa), South Korea.
PHOTO
Upper: Echizen-coast, Wakasa Bay, Japan. Depth: 2 m. Length: Approx 8 mm. 2 Aug 2004. On Codiaceae kind. Photographer: Jun Imamoto. Lower: Nagashima Beach, Kagoshima prefecture, southern Japan, Pacific Ocean. Depth: about 6-10 metres. Length: 15 mm. 4 March 2003. muddy sand. Photographer: Rie Nakano
Body varies from pale to dark translucent green, with black rhinophores which are paler, almost bluish black towards the base. Body, and outer surace of a parapodia covered in scattered small white spots of variable size. Border of parapodia with white line. Reported to feed exclusively on a species of the green alga Codium. Grows to approximately 30 mm.
From messages on the Forum from South Korea, it seems possible that Elysia flavomacula Jensen, 1990, is a colour variant with a bright yellow patch on the head. On the lower photo here on the Fact Sheet, there is a faint - but quite distinct - yellow patch.
This species is of particular interest as it was the subject of one of the earliest studies on solar powered sea slugs, with a detailed report by Kawaguti and Yamasu in 1965 demonstrating the presence of algal chloroplasts, not unicellular algae, in animal cells. Electron microscopy revealed that the green structures housed in the digestive cells of Elysia atroviridis were structurally identical to the chloroplasts in the green alga Codium fragile, upon which the sea slug was observed to feed.
- Baba, K. (1955). Opisthobranchia of Sagami Bay, Supplement. Tokyo: Iwanami Shoten.
- Kawaguti, S. & Yamasu, T. (1965) Electron microscopy on the symbiosis between an elysioid gastropod and chloroplasts of a green alga. Biological Journal of Okayama University, 11: 57-65.
Rudman, W.B., 2005 (June 17) Elysia atroviridis Baba, 1955. [In] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/elysatro
Related messages
Elysia atroviridis from Sth Korea
June 27, 2005
From: Dong Bum Koh
Dear Bill and others,
Last week I had a holiday in Bali. Especially Ubud is very impressive small village for me.
I read all messages on Elysia atroviridis / flavomacula in your Forum and thanks for them. Here are another photos of what I think is Elysia atroviridis from Sth Korea.
Locality: Hwa Soon. Jeju island, South Korea. Depth: 3 m. Length: About 10 mm. 19 Dec. 2004. Sandy bottom. Photographer: Byung Ro Youn
Best regards,
Dong Bum Koh
drkoh@seasee.co.kr
Koh, D.B., 2005 (Jun 27) Elysia atroviridis from Sth Korea. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/14126
Dear Koh,
Thanks for these. Your initial question and the subsequent discussion have been instrumental in us being able to sort out the identity of E. flavomacula. These photos show the large whitish glands at the parapodial edge which Kathe Jensen mentioned were a feature of E. flavomacula.
Best wishes,
Bill Rudman
Re: Japanese Elysia atroviridis with yellow spot
June 23, 2005
From: Kathe R. Jensen
Dear Bill,
Regarding the diet of Elysia atroviridis / flavomacula [message #14111], it is not unlikely that it will feed on different algae in different localities. We see the same thing in the common European Elysia viridis - the teeth actually look different. The teeth that I studied in E. flavomacula seemed to be typical "Cladophorales-teeth", i.e. rather broad, straight blades with denticles along the edge. In animals feeding on Codium I would expect the teeth to have narrower blades with curved tips and maybe "flanges" along the sides. I guess I could recheck the E. atroviridis radula. I did not have access to SEM at the time, so I only made drawings from light microscope slides.
Best wishes,
Kathe
krjensen@snm.ku.dk
Jensen, K.R., 2005 (Jun 23) Re: Japanese Elysia atroviridis with yellow spot. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/14117Thanks Kathe,
Bill Rudman
Re: Japanese Elysia atroviridis with yellow spot
June 22, 2005
From: Kathe R. Jensen
Dear Bill and others,
Concerning the yellow-spotted Elysia [#14078 ]
I have been trying to find a slide of the Elysia atroviridis that I collected in Hong Kong in 1983 because I think that one specimen had the small yellow spot that is also seen in Leslie Chan's photo [message #4895]. However, I still haven't found it - and in any case, I think the picture was taken by Brian Darvell (I don't think I had a macro-lens at the time).
I am quite prepared to accept the synonymy. In fact, I suggested that possibility in the description of E. flavomacula. I would be really interested in seeing egg masses of E. atroviridis both from Japan and other places. The specimens I described as E. flavomacula were all immature, even at size 9mm (live).
Best wishes,
Kathe
krjensen@snm.ku.dk
Jensen, K.R., 2005 (Jun 22) Re: Japanese Elysia atroviridis with yellow spot. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/14111Thanks Kathe,
I agree that some egg masses would be useful. You mention that in the laboratory your E. flavomacula fed on Chaetomorpha antennina and probably Cladophoropsis sp. while E. atroviridis is reported to feed on Codium. Does this sound inconsistent to you or is it possible that juveniles feed on different algae, or that lab conditions had affected them?
Best wishes,
Bill Rudman
Photos of Elysia atroviridis from Japan
June 19, 2005
From: Jun Imamoto
Dear Bill,
Following your request [message #14073], here are some photographs of Elysia atroviridis. I am happy for them to be included on the Forum for reference.
Locality: Echizen-coast, Wakasa Bay, Japan. Depth: 2 m. Length: Approx 8 mm. 2 Aug 2004. On Codiaceae kind. Photographer: Jun Imamoto
Best Regards,
Jun Imamoto
imamoto@umiushi.info
Dear Jun,
Thanks for these photos. It seems from these photos that there is at least one large whitish gland at the parapodial edge. In an earlier message Kathe Jensen mentioned she couldn't see large glands, which were characteristic of Elysia flavomacula in Koh's photos from Sth Korea. I have included a close-up alongside to show the characteristic filaments which extend from its food plant, Codium, and its relatives, to give the plant a furry appearance under water.
Best wishes,
Bill Rudman
Japanese Elysia atroviridis with yellow spot
June 19, 2005
From: Rie Nakano
Dear Dr.Rudman and Atsushi,
Following your request [message #14073], here are some photos of Elysia atroviridis from Japan. Elysia atroviridis is commonly seen in winter and spring.
Locality: Nagashima Beach, Kagoshima prefecture, southern Japan, Pacific Ocean. Depth: about 6-10 metres. Length: 15 mm. 4 March 2003. muddy sand. Photographer: Rie Nakano
Sincerely,
Rie
rie@divers.ne.jp
Dear Rie,
Thanks for these photos. With Jun Imamoto's photos [#14076], it greatly helps clarify this species for me. Of particular interest is your lower right photo which shows an animal with a faint yellow spot on the head, which was considered to be a characteristic of Elysia flavomacula, and is the feature which gave the species its name.
From these photos I think we can be fairly sure that Elysia flavomacula is a synonym of Elysia atroviridis.
Best wishes,
Bill Rudman
Koh's Elysia is Elysia atroviridis
June 17, 2005
From: Atsushi Ono
Dear Bill and Kathe,
Concerning messages #14009, #13963. #14054:
I think that Koh's elysiid looks like Elysia atroviridis Baba, 1955. E. atroviridis is found throughout Japan ,except in Hokkaido and Okinawa.
Please refer to: Baba, K. (1955). Opisthobranchia of Sagami Bay, Supplement. Tokyo: Iwanami Shoten.
Sincerely,
Atsushi Ono
ononini@cosmos.ne.jp
Ono, A., 2005 (Jun 17) Koh's Elysia is Elysia atroviridis. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/14073Dear Atsushi,
Thanks for this comment. This species was described by Baba without a colour illustration so it sometimes difficult for us without a personal knowledge of the Japanese fauna to re-identify some of his species. After doing a quick search I see that the species which is commonly recognised as E. atroviridis is identical to Koh's photos. This of course raises the question of whether Elysia flavomacula is a distinct species or a colour form. While Kathe Jensen's original specimens of E. flavomacula from Hong Kong [see message #14009] look a bit different, Leslie Chan's [#4895], also from Hong Kong, look identical to Koh's photos, except for the yellow spot. Before re-identifying Koh's animals I will wait for Kathe's comments.
If anyone could send me some photos of Elysia atroviridis from Japan to include on the Forum, for comparative purposes, I would be grateful
Best wishes,
Bill Rudman
Another Elysia flavomacula?
June 16, 2005
From: Dong Bum Koh
Dear Bill & Kathe,
Concerning messages #14009, #13963:
Thanks for your detailed descriptions for this animal.
Here is another photo of Elysia flavomacula taken several days ago in East Sea. It also hasn't a yellow spot on its head.
Locality: Young Duck. Kwang Won Prov., South Korea, East Sea. Depth: 11 m. Length: 30 mm. 09 June 2005. Photographer: Gwang Bouk Kim
Best regards,
Dong Bum Koh
drkoh@seasee.co.kr
D. B. Koh, 2005 (Jun 16) Another Elysia flavomacula?. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/14054Thanks Koh,
Bill Rudman
Elysia flavomacula? from South Korea
June 9, 2005
From: Dong Bum Koh
Dear Bill,
Here are some photos of what I think is Elysia flavomacula Jensen, 1990.
Locality: Ul Jin, Kyung Book Province, South Korea, east coast. Depth: 9 m. 01 June 2005. Photographer: Unknown. Photo Credit to Poong Deung Publishing company
Best regards,
Dong Bum Koh
drkoh@seasee.co.kr
D. B. Koh, 2005 (Jun 9) Elysia flavomacula? from South Korea. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/13963Dear Koh,
I will be very interested in hearing Kathe Jensen's opinion on this species. It certainly looks like Kathe's photos of that species, but one of the characters of Elysia flavomacula is the yellow spot on the centre of the head, which your animals lack.
Best wishes,
Bill Rudman
Elysia flavomacula from Hong Kong
July 24, 2001
From: Leslie Chan
Dear Dr.Rudman,
Thank you very much for the detailed description of my Elysia and other nudibranchs. I hope you can ID this photo of an Elysia I saw recently.
Steep Island, Hong Kong. 8m depth. 1.3 cm in length.
Best regards,
Leslie.
leslie@lesmart.com
Dear Leslie,
You are definitely finding some interesting animals. They are all very useful in understanding the shape and colour of these animals. This Elysia flavomacula which I don't think has been illustrated before in colour. As I note at the top of the page, it was described by Kathe Jensen (1990) from Hong Kong and I don't think has been found elsewhere.
Best wishes,
Bill Rudman
