Noumea purpurea Colour Group
How to differentiate the species.

PHOTO

The Noumea purpurea 'Colour group' of chromodorid species are all pink or purple with a whitish border and whitish longitudinal lines on the body. I have used often used the concept of Colour Groups in my work on chromodorids because it is an easy way to compare similarly colourde species. There is no suggestion that species of a colour group are necessarily closely related, in fact tey are often in different genera.

Rather than try and describe the differences I have illustrated all the species and suggest you go to the relevant pages for more detailed information. How do we know two very similarly coloured species are different? In most cases there are quite significant anatomical differences, especially in radular morphology. This is not much use in the field. With living animals check the colour of the gills and rhinophores, see if there is any indication of the type of mantle glands around the mantle edge. Check the colour of the foot and note whether the gills rhythmically flicker or wriggle when the animal is crawling along.

References:
•Rudman, W.B. (1984) The Chromodorididae (Opisthobranchia: Mollusca) of the Indo-West Pacific: a review of the genera. Zoological Journal of the Linnean Society 81: 115-273.
•Rudman, W. B. (1986) The Chromodorididae (Opisthobranchia: Mollusca) of the Indo-West Pacific: Noumea purpurea and Chromodoris decora colour groups. Zoological Journal of the Linnean Society 86(4): 309-353.

Authorship details
Rudman, W.B., 1999 (December 3) Noumea purpurea Colour Group How to differentiate the species.. [In] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/noumpur2

Related messages


On Noumea norba, N.purpurea, N.varians etc

December 4, 1999
From: Maki Yamamoto

Dear Bill
Recently I've read your paper in 1986 that said Noumea norba, N. varians and N. purpurea are the same. They're synonyms, and the valid name is N. purpurea. But now, they do not exist on your species list.
Where are they, especially Noumea purpurea, going?

Maki Yamamoto

maki-y@mtj.biglobe.ne.jp

Yamamoto, M., 1999 (Dec 4) On Noumea norba, N.purpurea, N.varians etc. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/1631

Dear Maki,

Your message arrived just as I was finishing a series of pages on a group of species which are very similar in colour to Noumea purpurea. In 1986 I thought N. purpurea and N. norba were the same species, but not N. varians. If you look at my message about those pages, it should answer your question.

The reason we consider some of these species to be different is nothing to do with slight colour differences (an extra spot here or a coloured line there), it is based on quite major differences in their internal anatomy, such as the shape of their reproductive system and radular teeth. After the anatomy has told us that there are different species, we have to find some way to identify the living animals without having to cut everyone of them up! That is why we have to look very carefully at their colour patterns to find differences, however slight, which are unique to a particular species.

You mention that Noumea purpurea wasn't in the Species List. The list only includes those species that I have a page for in the Forum. It is not a list of all the world's species. Now that I have included a page for Noumea purpurea it is in the list.

If you have any other questions or photos you want identified I am happy for you to send them.

Best wishes,
Bill Rudman.

Rudman, W.B., 1999 (Dec 4). Comment on On Noumea norba, N.purpurea, N.varians etc by Maki Yamamoto. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/1631

On the Noumea purpurea Colour Group

December 4, 1999
From: Bill Rudman

I have been preparing for some time some pages on species of Noumea and after receiving Yasuhiro Shirai's photo of Noumea purpurea and Maki Yamamoto's question on Noumea norba etc, I decided to concentrate on the Noumea purpurea Colour Group. Now that much more information is available on Noumea purpurea we can see that it is clearly different from Noumea norba.

I have added a comparative page on the Noumea purpurea Colour Group and added or enhanced the pages on the following species:
•Durvilledoris pusilla
•Noumea varians
•Noumea varians
•Noumea norba
•Pectenodoris trilineata
•Durvilledoris similaris
•Hypselodoris maculosa
•Durvilledoris lemniscata
•Noumea alboannulata
•Chromodoris? sp. 6
•Noumea purpurea

Best wishes,
Bill Rudman.

Rudman, W.B., 1999 (Dec 4) On the Noumea purpurea Colour Group. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/1640