Nudibranch identification

[Naif 1]

I'm a nudibranch lover I found some of them where I dive usually Red Sea but still not yet familiar with names. Any book you guys recommend ? 

I will post some pictures 

[Architeuthis 182]

This here covers the Indopacific, including the red Sea: https://www.amazon.de/Nudibranch-Sea-Slug-Identification-Indo-Pacific/dp/1878348671/ref=sr_1_1?__mk_de_DE=ÅMÅŽÕÑ&crid=2K7E3LJ64T0AF&keywords=Nudibranch+%26+Sea+Slug+identification&qid=1679983295&sprefix=nudibranch+%26+sea+slug+identification%2Caps%2C116&sr=8-1

also available here: http://fishid.com/#printed-books

 

 

Wolfgang

Edited March 28 by Architeuthis

[Kraken de Mabini 202]

Hi, first about books, the ones I know of deal with the IndoPacific and Asia, you would need to look for books on Mediterranean and Red Sea nudibranchs.  You might ask the staff at New World Publications, or better a professional librarian.  Neville Coleman's book is an excellent all around source for nudibranchs, together with Terry Gosliner's books.

Some rough diagnosis on these five photos are:

#1: Elysia species 3     #2 No idea, but it might be a Phyllodesmium species   #3 and #5 Goniobranchus ?sp, and #4 is a Goniobranchus geminus.

Please do not hold me to these diagnoses as they are approximate and based on Indopacific nudibranch books. Nathalie Yonow has written a book on 'SeaSlugs of the Red Sea', but I don't have it.  Once you have taken more nudi photos, please post them here.  Several of my friends have discovered new nudibranchs, now named after them, maybe you will discover some new Red Sea nudibranchs.

[Luko 38]

#2 Phyllodesmium crypticum

# 3 and 5 Glossodoris hikuerensis

 

[Kraken de Mabini 202]

Good try, but not quite, as the mantle of the nudi in photos #3 and #5 has a green ribbon and white edge that do not match the mantle's blue ribbon of Glossodoris hikuerensis. 

Another possibility is that both animals are the same species, with their different mantle color differences being a result of different diets. For precise clasification,  DNA might be the best way to find out if they are the same or different species.

Reference: Coleman, N. Cobb, G. and Mullins D.: Nudibranchs Encyclopedia, 2015.  p. 128, lower right photo.

Edited May 16 by Kraken de Mabini

[Luko 38]

On 5/16/2023 at 6:51 PM, Kraken de Mabini said:

Good try, but not quite, as the mantle of the nudi in photos #3 and #5 has a green ribbon and white edge that do not match the mantle's blue ribbon of Glossodoris hikuerensis. 

According to Erwin Kohler, Glossodoris hikuearensis doesn't necessarily have a blue ribbon on the mantle

Check this out :  http://www.medslugs.de/E/Pac-W/Glossodoris_hikuerensis/Glossodoris_hikuerensis_10.htm there are multiple examples and variations (I take E.Kohler's website as one of the most up to date source compared to printed books). Coleman and even NSSI2 seem to be outdated (sometimes with blatant errors such as mismatching the blue/yellow costasiella with stiliger, giving names which are not accepted by WORMS like Bornella adamsii, etc.)

On 5/16/2023 at 6:51 PM, Kraken de Mabini said:

For precise clasification,  DNA might be the best way to find out if they are the same or different species.

It can also gives way to a dead end or a step back because unless there is a significant difference in the eigenvalues, at some time automatic clustering -the process that either merges or discriminates observed specimens into species- is often a matter of choice for the taxonomist (Disclaimer : i have a statistics background although not focused on biology, I faced this issue for other type of matters ) : when does a group/sp is different from the other one, what level of difference will you accept.  I believe that's what happened in the recent works where some nudibranch groups where either merged into a big one or a former known specie that was supposed to be one was divided into a absurd number of various sp. all carrying sp. numbers. I read somewhere that even for the initiators of the most recent classifications, it was a work in progress, not to mention there are some marine biologists who do not agree even with the naming of the larger families (esp. Tenellia).     

IMO for our photographer's purpose, I don't think every nudibranch needs to be killed and sliced into bits for the sake of checking its name without any further comprehension (I prefer to know where it feeds, so I can look for it rather than which sp number it was named). 

Edited May 19 by Luko

[Kraken de Mabini 202]

All of Luko's points are valid and well taken.  The subjective and rather erratic nature of nudibranch taxonomy is one of the main reasons why Dr Terry Gosliner, of the California Academy of Sciences, has undertaken the rather enormous task of revising and bringing it up to date in a systematic manner, basing the taxonomy on DNA.  

Edited May 19 by Kraken de Mabini