Rostanga from New Caledonia

August 31, 2006
From: Jean-François Hervé

Dear Dr Rudman,

Thank you for your answer [message #17621] concerning the Hypselodoris. Here are some more photos of the orange thing which you think may be a dorid.  I didn't realise it was a dorid when I photographed it - perhaps I wasn't awake! I guess it was about the same length as the Hypselodoris

Locality: Noumea, 10 m, New caledonia, Pacific Ocean, July 2006. Length: approx 15 mm. Photographer: Jean-François Hervé

Thank You very much.
Jean-François Hervé

Hervé, J-F, 2006 (Aug 31) Rostanga from New Caledonia. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from

Dear Jean-François,

When I first saw it in your earlier photo on the purple sponge I was pretty sure it was a species of Rostanga, but I was puzzled at it being on the purple sponge which is not the type of sponge that species of Rostanga feed on. I can see in these new photos however that there is also an orange sponge, of the same colour as the Rostanga, mixed up with the purple colony. For some reason, it only has one [brown] rhinophore visible.

Most species of Rostanga are orange or red with a spiculate texture caused by the close packed caryophyllidia. External differences can be found in the shape of the rhinophores and in biological characteristics such as nature of egg mass, size of eggs, and food sponge. Internally, radular morphology is the most useful character. Because a photo like this doesn't really give me enough information to identify your animal to species, I can't be 100% sure of its name. However I have found Rostanga bifurcata in New Caledonia before, and the shape and the colour of the rhinophores are the same, so I will tentatively identfy it as that species.

Best wishes,
Bill Rudman

Rudman, W.B., 2006 (Aug 31). Comment on Rostanga from New Caledonia by Jean-François Hervé. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from


Rostanga bifurcata

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