Mexichromis festiva from South Africa

April 25, 2008
From: Colin Ogden

Hi Bill,
Could this be a Mexichromis festiva, or is it a Mexichromis cf mariei?
I think it looks like M. festiva, but they are not supposed to be here. (I know the nudis don't read our books so they don't care about where they are supposed to be and are full of surprises)

Locality: Sodwana Bay, 20 metres, South Africa, Indian, 05 September 2007, reef. Length: 25 mm. Photographer: Colin Ogden.


Ogden C M, 2008 (Apr 25) Mexichromis festiva from South Africa. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from

Dear Colin,

I think I will just call it Mexichromis cf mariei. Basically I suspect a number of these species may be just forms of each other. When I was at school, I was a keen shell collector and belonged to a shell club at the Auckland Museum and if we were very lucky the great New Zealand expert A.W.B. Powell would visit and help identify any problem shells we brought along. I had made friends with a trawlerman who used to give me rare finds from offshore New Zealand. One group of particular difficulty were volutes. New Zeland either had a  few species which were very variable in shape and colour or a lot of species each with very small geographic ranges.  Over some months I took the same shell along with different locality data and got 3 different species names. Apart from one friend, I never told anyone I did it, but it did give me an insight into the problems of identifying animals from single specimens, and the dangers of being an 'expert'. I guess Mexichromis could be my penance for tricking Dr Powell so many years ago.

Best wishes,
Bill Rudman

Rudman, W.B., 2008 (Apr 25). Comment on Mexichromis festiva from South Africa by Colin Ogden. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from

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