Tambja affinis v. Roboastra luteolineata

April 23, 1999
From: Ross Armstrong

Hi Bill
Your e-mails re what we have previously referred to as Tambja affinis actually being Roboastra luteolineata has generated quite a bit of interest at our last Northland Underwater Photographic Society meeting.

Peter Snooks and Antony Syms, two keen photographers from Dargaville, have provided me with some of their photos for you to check. [top two are Peter's, lower two are Antony's] They have checked their photos against those shown in Helmut Debelius's book and are quite certain they match the nudibranch Helmut identifies as Tambja affinis.

I know that you were not sure if Helmut was correct is his book and have attached their photos for your expert opinion.

kind regards

Ross Armstrong
New Zealand


Armstrong, R., 1999 (Apr 23) Tambja affinis v. Roboastra luteolineata. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/799

Dear Ross,
Whatever Helmut Debelius has in his book, the only way to know what an animal is, is to have a look at its anatomy and to refer to the original descriptions of the species. I can assure you that the animal you have sent me photos of, has an internal anatomy which makes it a member of the genus Roboastra. Apart from other features the radular teeth are very distinct. When I get a new scanner I've bought to work, (I seem to have bought a lemon and I've threatened the manufacturer to tell you all the make and model if they don't make it work!), I aim to put some radular photos up to show you.

Another very distinctive feature is the long prominent oral tentacles which can be seen in the photo alongside. Now why isn't it Tambja affinis? If we go back to the original description of that species as Nembrotha affinis Eliot, 1904, he clearly illustrates the radula of a species of Tambja. That alone shows that your animal cannot be the same as Eliot's. Your animal is identical in colour and anatomy to Roboastra luteolineata as first described by Baba in 1936, and more fully by Hamatani & Baba, 1976.

There's not much more to say. I'm afraid that although books with lots of beautiful colour pictures are becoming quite abundant as the costs of colour printing fall, taxonomists and research workers studying these animals have not become correspondingly more abundant. Because of this, we will have to expect a level of inaccuracy in many popular works.

Researching the names, relationships and biology of most groups of animals is a slow time-consuming task. I know our 'clients', such as interested divers, photographers etc, are impatient for the correct name, but unfortunately until more funds are provided for basic research it will be a slow haul.

Bill Rudman.

Rudman, W.B., 1999 (Apr 23). Comment on Tambja affinis v. Roboastra luteolineata by Ross Armstrong. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/799

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