Rostanga rubra - eggs ?

July 28, 2003
From: Jean-Pierre Bielecki

Hi Bill
Here is one other shot of the same slug that Marina Poddubetskaia sent you in her previous message.

The slug is exactly in the position when I found it, that is to say into this piece of broken shell (Pinna nobilis). When I saw it I was too excited to see the eggs near it. Do you think these eggs could belongs to this animal or it is a real stroke of luck?
Best wishes

Bielecki, J-P., 2003 (Jul 28) Rostanga rubra - eggs ?. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from

Dear Jean-Pierre,
The egg ribbon is just a co-incidence. As far as I know all species of Rostanga produce orange or orange-red eggs possibly incorporating pigment from their sponge food. Have a look at Baki Yoke's message for photos of this species' egg ribbon. I can't say much about the white egg mass in your photo. It may be an opisthobranch but could be a snail of some sort.

I have included alongside a closeup of part of your lower left photo. With a bit of digital magic I was able to enhance the detail of the mantle to show what the caryophyllidia or 'bristles' on this species look like. The bristles, or tubercles, which give the mantle its furry appearance, are elongate structures with a central terminal rounded knob, and below it a ring of upwardly directed pointed spicules.
Best wishes,
Bill Rudman

Rudman, W.B., 2003 (Jul 28). Comment on Rostanga rubra - eggs ? by Jean-Pierre Bielecki . [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from


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