Madrella ferruginosa from South Africa

January 9, 2001
From: Valda Fraser

Dear Bill
Such a cute creature ... but what a devil to photgraph! Unfortunately this is the best that I could do. I think it is perhaps Madrella ?. When I tried to move it, a mustard coloured fluid came out of it and it stained my fingers.
Locality: Sodwana, north coast KwaZulu-Natal, SOUTH AFRICA, 15m
Date: Nov 2000
Size: 12mm
Valda Fraser

Fraser, V., 2001 (Jan 9) Madrella ferruginosa from South Africa. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from

Dear Valda,
Yes this is indeed a Madrella, probably Madrella ferruginosa. There is an interesting puzzle surrounding the large brownish tropical form and a bright red fprm from southern Australia which is named Madrella sanguinea. There is very little anatomically to separate the two and it will probably need a better understanding of the biology of the two to know whether they are two distinct species or not. If they prove the same then the name M. sanguinea is three months older than M. ferruginosa, both being named in 1864.

The yellow substance that dyed your fingers is exuded by glands or sacs at the base of each ceras. Both species produce this substance which is probably from the bryozoans they feed on. And yes they are very difficult to photograph.
Best wishes,
Bill Rudman.

Rudman, W.B., 2001 (Jan 9). Comment on Madrella ferruginosa from South Africa by Valda Fraser. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from

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