Re: Thuridilla cf. neona? from Great Barrier Reef

Note added 31 Oct 2005: This is most probably a colour variant of  T. neona. See message #15140.

Dear Julie,
Thanks for the interesting photo. It reinforces my feelings that we haven't got this group of species sorted out properly at present. I agree with Skip Pierce's comments [#15109] that we need to use colour with care, but every new photo of this T. neona - T. indopacifica colour group throws up inconsistencies. And we need to consider Thuridilla sp. 3 and Thuridilla sp. 4. as well. 

Your animal certainly has the diagonal yellow, black and bluish bands on the rhinophores as in T. neona, but the color bands on the parapodial border are quite different. In T. neona the orange-yellow, black and blue marginal bands are thin lines whose width does not vary along their length. Both the photos on the Forum, and Gosliner's description show this. In your animal the orange marginal line varies in width along its length, there are then thin yellow and blue lines which don't vary in width, and then a series of large blue patches. To add to the confusion, your animal and Daniel Foote's although the same in most colour features, differ in the color of the head. These animals, which I am calling ' Thuridilla sp. 4' also differ from both T. neona and T. indopacifica in the way the orange mantle border varies in width as in T. undula.   Thuridillasp. 4. therefore has the general colour of T. indopacifica, the rhinophore bands of  T. neona, and the wavy, 'undulate' orange border of T. undula.

If anyone else has photos to throw into the melting pot and hopefully throw light on this puzzle, they would be very welcome.

Best wishes,
Bill Rudman