More on Chromodoris cf. colemani & C. hamiltoni

July 7, 2001
From: Bernard Picton

Hi Bill,
I'm still puzzling over this, I'm now convinced that there is a species which is widespread East Africa to Indonesia, Okinawa? (Bob Bolland's site as C. hamiltoni?) which is not true Chromodoris hamiltoni and which grades into (is) your Chromodoris cf. colemani. I've attached three more pictures to add to the three I sent yesterday which come closer to C. hamiltoni. They differ in my opinion in having a punctate blue background (more solid in C. hamiltoni) bolder black lines without blurred edges, black lines partly replaced with brown pigment or with intermediate brown lines. There is a moderately broad white band between the black lateral lines and the orange border which extends along the sides of the body (wide band at head and tail in C. hamiltoni, but little or no band at sides). The orange border is yellow-orange rather than orange-red in C. hamiltoni.

The three photos were taken in NW Bali, Indonesia in March 1996.


Picton, B., 2001 (Jul 7) More on Chromodoris cf. colemani & C. hamiltoni. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from

Thanks Bernard,
I didn't post this message yesterday as promised, as I was still trying to think of something enlightening to say. Words of wisdom still escape me, so I'll post your message without them.

As I said before, I am not how many species have these orange lines and if there is more than one species, whether orange lines can be present or absent within a single species. I suspect that all your photos in this message and your earlier one are the s ame species. Suffice to say I have over many years built up a dossier of anatomical dissections and radula photos of this colour group but still can't find convincing differences. I assume mimicry is probably involved, greatly complicating the situation. And if mimicry is involved in only one part of the geographic range, it is possible that there are a number of species which only resemble each other in regions of geographic overlap.

Best wishes,
Bill Rudman

Rudman, W.B., 2001 (Jul 7). Comment on More on Chromodoris cf. colemani & C. hamiltoni by Bernard Picton . [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from

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