Re: Costasiella ocellifera - one species or two?

March 8, 2004
From: Marina Poddubetskaia

Dear Bill,
I was interested in reading your thoughts about Costasiella ocellifera larval development [#12361]. It reminded me of a little mystery I met in the Northern Bahamas. I'm not sure this information will be useful for you, but here is the story...

One day I was snorkelling in the Bimini Road site. It is a sandy area with many alga including the Udotea in the lower photo of my message about Elysia papillosa from Northern Bahamas [#12335]. Please, note that this alga looks similar to the one in my message #12277, but I'm sure it's not the same.

So, in Bimini Road this Udotea is very common but scattered over a large area. I noted there that many leaves of this alga had one (and only one) egg-ribbon like in attached photos A and C. These eggs was so numerous that I wanted to discover the sacoglossan which lays them. For up to one hour I checked all the algae of this species and I didn't find any sacoglossan on it, only egg-ribbons. It was completely incredible to see such a huge number of eggs and no one living animal. After my snorkelling I continued with the scuba dive in the same area. At the end of my dive I succeeded in finding one Elysia papillosa on this alga: it is the one in my message #12335.

However I can't decide whether these eggs all belong to one species. In fact, these eggs look very similar to the Costasiella ocellifera ones from the Southern Bahamas [#12277]. But here they clearly correspond to a direct larval development. Moreover, the lower left animal (Costasiella ocellifera) from my message #12276 was found in the same area, but on the sand. So, we can be sure that Costasiella ocellifera is present here too.

Do you think these eggs could belong to Costasiella ocellifera? If so, it would be an illustration of the direct larval development in this species. As for the second egg-ribbon [photo B], I saw it only one time and it probably belong to another species.

Bimini Islands, Bahamas, Western Atlantic. Site: Bimini Road. Depth: 1-2m. February 12, 2004.
Diameter of egg ribbons: A: 6mm., B: 7mm., C: 7mm
Photos: Marina Poddubetskaia - Nembro website

I hope this little mystery is interesting for you.
Best wishes,
Marina.

nembro@nembro.info

Poddubetskaia, M., 2004 (Mar 8) Re: Costasiella ocellifera - one species or two?. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/12374

Thanks Marina,
It's certainly irritating when you find lots of eggs and no obvious layers. Both the ribbons you illustrate here are different from your earlier photo of the egg ribbon of Costasiella ocellifera. Also Costasiella seems to feed exclusively on Avarianvillea so it is unlikely to have laid its eggs on a species of Udotea.

Elysia papillosa has lecithotrophic development [see Jensen message #5967] so it is possible the large eggs in your common egg,ass belong to that species.
Best wishes
Bill Rudman

Rudman, W.B., 2004 (Mar 8). Comment on Re: Costasiella ocellifera - one species or two? by Marina Poddubetskaia. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/12374

Factsheet

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