Re: Chromodoris hamiltoni ? from India

May 6, 2010
From: Franco De Lorenzi

Concerning message #23138:

Dear prof. Rudman reading this message I looked at a photo I have of this species but, at first I thought it might be C. hamiltoni, now I wonder if it is Chromodoris colemani or Chromodoris cf. colemani.
In effect there is not much orange background on it.

Locality: Cebu, 18 Metres, Philippines, indopacific ocean, august 2005, coral. Length: 25 mm. Photographer: Franco De Lorenzi.

Thanks for help.

De Lorenzi, F., 2010 (May 6) Re: Chromodoris hamiltoni ? from India. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from

Dear Franco,

This is a very good example illustrating the difficulties we still have in distinguishing some of these species with longitudinal black lines. Your animal certainly looks like some specimens of C. hamiltoni in having the secondary brown lines, but in that species the orange border goes right to the mantle edge, wherEas in your animal there is a clear white band right at the edge.

One common west Pacific species with a submarginal orange band like this is C. magnifica, which seems to quite variable in the number and type of black lines it has, but in that species the mantle skirt is very wide whereas your animal belongs to a group of species with relatively narrow sides to the mantle. At the moment I have been putting animals with your colour pattern in a group I have called Chromodoris cf. africana, but some of those have the orange border right at the edge, so there is probably more than one species mixed up in this lot as well.

Sorry I can't be more help but this is definitely a group in need of more work. Unfortunately I don't think anatomical differences are going to be distinct enough to provide resolution. Some will say that DNA studies will resolve it, wich may be so, but I suspect what is really needed is some good field workers who can study these animals as populations. Most of our information at the moment is from a relatively few animals collected on short field trips and random photos taken by interested divers. While all this is valuable, as you can see from my comments, we seem to have reached a plateau where we can recognise problems rather than solving them.

Best wishes,
Bill Rudman

Rudman, W.B., 2010 (May 6). Comment on Re: Chromodoris hamiltoni ? from India by Franco De Lorenzi. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from

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