Chromodoris geometrica & C. conchyliata

June 27, 2005
From: Colin Ogden

Hi Bill,
These photos were taken recently in Sodwana Bay.

Locality: Sodwana Bay, South Africa, Indian Ocean. Depth: 19 to 24 metres. Length: 25 mm. May and June 2005. Coral reef. Photographer: Colin Ogden

I believe the nudi in the upper photo is a Chromodoris conchyliata because of the reddish tinge to gills and rhinopores, and also the yellowish pustules on its back compared to the other 2 nudis which I think are the Chromodoris geometrica. Although these 2 also appear to be slightly different, they do have a black section on their tails just below the "mantle"
Am I correct in my ID.

Ogden C M, 2005 (Jun 27) Chromodoris geometrica & C. conchyliata. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from

Dear Colin,
You are correct in your identifications. Have a look at Valda Fraser's message [#2570] asking about this very question. When I first reported on C. conchyliata from Kenya in 1973 I thought it was probably a regional colour form of C. geometrica but the information we now have on the Forum, and the existence of both 'forms' in South Africa, suggest they are both good species. The most obvious external difference is the colour of the gills and rhinophores - green-tipped in C. geometrica and orange-tipped in C. conchyliata - but your certainly the black markings on the posterior foot of C. geometrica may also be a good external difference.

As I said to Valda, it would be nice to get photos of their food sponges and egg ribbons.
Best wishes,
Bill Rudman

Rudman, W.B., 2005 (Jun 27). Comment on Chromodoris geometrica & C. conchyliata by Colin Ogden. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from

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