Roboastra sp. from Brazil

November 20, 2003
From: Marcelo Krause

Hi Dr. Rudman,
Some time ago I mailed some pictures for you of Brazilian sea slugs. Well, this weekend I found a different one, that I never have seem before. I contacted Carlo Magenta, a Brazilian sea slug expert and he suggested that the species might be the chromodorid Hypselodoris picta lajensis. I have seen that species before (they are quite common) but the color and perhaps even the stripes of the one that I photographed are different. I am sending you the link to the pictures, in case you want to take a look. I don't know if it is only some color variations or it may be a different kind,

Best regards,
Marcelo Krause

Krause, M., 2003 (Nov 20) Roboastra sp. from Brazil. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from

Dear Marcelo,
This is an interesting find. Although it has similarities to Hypselodoris picta lajensis in general colour, its shape is quite different. It is a member of the family Nembrothidae, and almost certainly a species of the genus Roboastra. In that genus the oral tentacles are very enlarged and rolled as can clealry be seen in your photos. Species of Roboastra are spectacular hunters, usually feeding on species of the related genus Tambja.

The only nembrothid I know from Brazil is Nembrotha divae Marcus, 1956 which was described as scarlet with white gills and white dots. From the radula description it is almost certainly a species of Tambja rather than Nembrotha. The only species of Roboastra that I know from the Atlantic is Roboastra europaea. It is somewhat similar in colour but is only known from the east Atlantic. Your animal is possibly an unnamed species.

I am intersted in your comment that Hypselodoris picta lajensis is quite common. If you ever see it feeding on a sponge or laying eggs I would be very intersted in photos as we know little about the biology of many of these animals
Best wishes,
Bill Rudman

Rudman, W.B., 2003 (Nov 20). Comment on Roboastra sp. from Brazil by Marcelo Krause. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from


Roboastra sp. 1

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