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Cuthona rubescens

Picton & Brown, 1978


Erling Svensen And this one - Cuthona rubescens? A 15 mm long specie - todays dive in Egersund harbour.

Bernard Picton one of my favourites....

Christian Skauge Yes, C. rubeschens :-)

João Pedro Silva It reminds me a bit of Klas Malmberg's photo on the "Unidentified" album: https://www.facebook.com/photo.php?fbid=443750715641352&set=oa.167103413400947&type=1&theater

Christian Skauge I'm thinking maye C. pustulata on that one ;-)

Jussi Evertsen Do not let the colour of the digestive tracts fool you - seems like this one also has superficial white pigmentation

João Pedro Silva It's also similar to this one, but the cerata have a different shape and there's a big difference in size between the rhinophores and the oral tentacles (the latter much shorter): https://www.facebook.com/photo.php?fbid=3222155353823&set=oa.167103413400947&type=1&theater

Message posted on NE Atlantic Nudibranchs on 13 Feb 2013
Klas Malmberg Aquatilis New picture on a little nudie that I would guess is a Cuthona rubescens - do you agree? Or is i something else?

Peter H van Bragt Yes, I could agree, as we can see here also the red pigment on the rhinophores. However it is faint.

Message posted on NE Atlantic Nudibranchs on 03 May 2012
Erling Svensen I am jelous, Dan. You have seen some nudies that I never have seen! Well, I put out two pictures from todays dive. Nice to be in the water again after so many days (3 days). This one is a Cuthona rubescens (I think).

Erling Svensen This one is a very rare one with ADHD.....!

Dan Bolt Hi Erling, well that goes both way as you have seen many I have not too! :)

Mick Otten So many days..... Are you already developing gills in stead of lungs? I envy the clear water your diving in. And foremost enjoy your pictures of nudies I have never seen!

Message posted on NE Atlantic Nudibranchs on 03 Mar 2012
Richard Yorke Could this be Cuthona rubescens. It seems that is the only nudibranch with redish bands half way up its rhinophores

David Kipling Where was this taken Richard?

Richard Yorke Just edited it to say Llyn Peninsula, the edit does not seem to have appeared :-(

Terry Griffiths Sorry Richard i would say not a bit more like F.bostoniensis very similar in colour too the one we get in the SW,will post you a photo of Cuthona rubescens.

Terry Griffiths

Richard Yorke If there was a picture in that I am not allowed to see it! The pictures of F.bostoniensis I have seen do not have the redish bands half way up its rhinophores

Terry Griffiths Sorry trying to sort it out

Richard Yorke No sign of lamellate rhinophores on mine like David's picture either (though his is a better picture).

Terry Griffiths Sent you the photo Richard.

Peter H van Bragt Juv. F. bostoniensis. C. rubes. does not have so many cerata

Peter H van Bragt Lamellate rhinophores are not always very prominent

Bernard Picton The cerata shape, shape of the white splash, pigmented oesophagous, all point to F. bostoniensis.

Richard Yorke Thanks for everyone's help

Richard Yorke Now I know more about what I am looking for I have found 2 more from the same dive! The third follows.

Richard Yorke The third

Sarah Bowen Your third one is Facelina auriculata (just to add another into the mix). And the one above it also seems to have a rosy hue behind the rhinophores; you can get orange colour-morphs of F. auriculata.

David Kipling The third has that almost-subliminal blue iridescence on it - classic F auriculata. Sorry Richard!

Richard Yorke Oh well! I will keep trying, practice can only help :-) I had assumed the 'rosy hue behind the rhinophores' was what Bernard had referred to as the 'pigmented oesophagous'. Still, my species list for that dive is getting longer!

Sarah Bowen Sadly, F. bostoniensis also has pigment. But the main difference seems to be that the cerata in F. auriculata are somewhat shorter, fatter and appear in groups whereas F. bostoniensis looks 'shaggy' if that makes sense. F. auriculata also tends to have splashes of white pigment around the tips, but F. bostoniensis only seems to have well-defined white tips.

Julia Nunn Facelina auriculats is a slim animal with bluish iridescence; bostoniensis is a fatter more robust animal, with no iridescence or very little

João Pedro Silva Julia, check the previous comments to see the photo identified as F. auriculata.

Message posted on NE Atlantic Nudibranchs on 01 Oct 2013
Terry Griffiths A bit of help with this one please about 10mm in length could be Cuthona amoena brown rings on rhinophores and yellow-white pigment or could it be a jve Cuthona rubescens thanks

Terry Griffiths Sorry about 5mm not 10mm .

Anna Nudi Burn How do you find these wee nippers, Griff?!

Terry Griffiths Just look for something out of place.

Anna Nudi Burn I think I need my eyes tested :D

Terry Griffiths Just think how bad it's for me.

Anna Nudi Burn I think I want to be like you when I grow up ;)

Christian Skauge I'm thinking Cuthona rubescens :-)

Brendan Oonk Let me start by saying that I have never seen C.rubescens in real life. But in none of the photos I've seen of C.rubescens it has got brown bands on its oral tentelacles, which C. Amoena has got. In this picture there seen to be (the start of) bands on the oral tentacles. So if this realy is a difference between the two, this is C.amoena

Anna Nudi Burn Seems like sound thinking!

Christian Skauge C. rubescens does not usually have bands on the oral tentacles, according to Thompson & Brown - indicating that they may occur. C. amoena should have reddish brown or olive bands below the tip of the rhinophores according to the same book. I find these bands a little too low for being "below the tip". But looking at the images of both species in Picton/Morrow's Field Guide, I tend to agree with you still... We don't get C. amoena in Norway, so I'm not familiar with it. Or maybe we do, after all? Perhaps Bernard Picton could help us out on this one - after all he helped describe C. rubescens in 1978 ;-)

Christian Skauge Re-examining my own images of this/similar species. It seems I have two different things... Difficult, and who knows what they look like when they are juvenile? You might be right about C. amoena Brendan - and in that case I may have the first image of this species from Norway :-)

Terry Griffiths Thanks all a new one for me too :-)

Kirstie Harris Terry - stop finding new ones! I have enough trouble finding all the old ones :)

Peter H van Bragt Hi Terry, I doubt that this could be C. rubescens. It lacks the continuous streak of white pigment on the oral tentacles. C. amoena is a fair option. The lack of white pigment spots on the cerata tips, the cnidosac being visible in these tips, white pigment spots on teh abck are indicative. Did you see and photograph any spawn close to this specimen and on what hydroid species did you find it? Could be usefull for the ID.

Christian Skauge I have read the descriptions in all my books now and come to the conclusion that I was probably wrong in suggesting C. rubescens. This means I need to talk to my Norwegian experts... I don't think C. amoena has been recorded in Norway, and we might have misidentified this. Please have a look at this image and tell me what you think: http://www.scubapixel.com/component/content/article/8-images/2437-1021-27032011-7885-Cuthona_rubescens.jpg

Rachel Shucksmith Christian looking at my photographs from Gulen, they look more like C. amoena than C. rubescens, although they are little small for me to photograph well.

Christian Skauge This is quite exciting, actually! I hope I'm wrong ;-)

Terry Griffiths Glad to have helped you out lol.

Christian Skauge ha ha thanks :D

Terry Griffiths Christian get off FB and get back to checking your books .

Rachel Shucksmith On habitas it says: The dorsal surfaces of the oral tentacles have a continuous band of white pigment, and this distinguishing feature is present even in juveniles. Which Terry's, yours Christian on Scuba pixel and mine from Gulen dont have....

Christian Skauge True, htat is one of things I noticed as well. This bugger is more speckled - but could it be a juvenile?

Rachel Shucksmith I do defiantly have C. rubens pics from Gulen as one of my individuals defiantly have the white band all the way along the oral tentacles, my other one is more speckled. They were also on different hydroids.

Christian Skauge Yeah, it seems to be two types.

Bernard Picton Christian, I think yours is C. rubescens. Juveniles of both these species have less pigment than adults, so they do get very difficult to identify at 5mm.

Message posted on NE Atlantic Nudibranchs on 06 May 2013
Richard Yorke Could this be Cuthona rubescens. It seems that is the only nudibranch with redish bands half way up its rhinophores

David Kipling Where was this taken Richard?

Richard Yorke Just edited it to say Llyn Peninsula, the edit does not seem to have appeared :-(

Terry Griffiths Sorry Richard i would say not a bit more like F.bostoniensis very similar in colour too the one we get in the SW,will post you a photo of Cuthona rubescens.

Terry Griffiths

Richard Yorke If there was a picture in that I am not allowed to see it! The pictures of F.bostoniensis I have seen do not have the redish bands half way up its rhinophores

Terry Griffiths Sorry trying to sort it out

Richard Yorke No sign of lamellate rhinophores on mine like David's picture either (though his is a better picture).

Terry Griffiths Sent you the photo Richard.

Peter H van Bragt Juv. F. bostoniensis. C. rubes. does not have so many cerata

Peter H van Bragt Lamellate rhinophores are not always very prominent

Bernard Picton The cerata shape, shape of the white splash, pigmented oesophagous, all point to F. bostoniensis.

Richard Yorke Thanks for everyone's help

Richard Yorke Now I know more about what I am looking for I have found 2 more from the same dive! The third follows.

Richard Yorke The third

Sarah Bowen Your third one is Facelina auriculata (just to add another into the mix). And the one above it also seems to have a rosy hue behind the rhinophores; you can get orange colour-morphs of F. auriculata.

David Kipling The third has that almost-subliminal blue iridescence on it - classic F auriculata. Sorry Richard!

Richard Yorke Oh well! I will keep trying, practice can only help :-) I had assumed the 'rosy hue behind the rhinophores' was what Bernard had referred to as the 'pigmented oesophagous'. Still, my species list for that dive is getting longer!

Sarah Bowen Sadly, F. bostoniensis also has pigment. But the main difference seems to be that the cerata in F. auriculata are somewhat shorter, fatter and appear in groups whereas F. bostoniensis looks 'shaggy' if that makes sense. F. auriculata also tends to have splashes of white pigment around the tips, but F. bostoniensis only seems to have well-defined white tips.

Julia Nunn Facelina auriculats is a slim animal with bluish iridescence; bostoniensis is a fatter more robust animal, with no iridescence or very little

João Pedro Silva Julia, check the previous comments to see the photo identified as F. auriculata.

Message posted on NE Atlantic Nudibranchs on 01 Oct 2013
Terry Griffiths A bit of help with this one please about 10mm in length could be Cuthona amoena brown rings on rhinophores and yellow-white pigment or could it be a jve Cuthona rubescens thanks

Terry Griffiths Sorry about 5mm not 10mm .

Anna Nudi Burn How do you find these wee nippers, Griff?!

Terry Griffiths Just look for something out of place.

Anna Nudi Burn I think I need my eyes tested :D

Terry Griffiths Just think how bad it's for me.

Anna Nudi Burn I think I want to be like you when I grow up ;)

Christian Skauge I'm thinking Cuthona rubescens :-)

Brendan Oonk Let me start by saying that I have never seen C.rubescens in real life. But in none of the photos I've seen of C.rubescens it has got brown bands on its oral tentelacles, which C. Amoena has got. In this picture there seen to be (the start of) bands on the oral tentacles. So if this realy is a difference between the two, this is C.amoena

Anna Nudi Burn Seems like sound thinking!

Christian Skauge C. rubescens does not usually have bands on the oral tentacles, according to Thompson & Brown - indicating that they may occur. C. amoena should have reddish brown or olive bands below the tip of the rhinophores according to the same book. I find these bands a little too low for being "below the tip". But looking at the images of both species in Picton/Morrow's Field Guide, I tend to agree with you still... We don't get C. amoena in Norway, so I'm not familiar with it. Or maybe we do, after all? Perhaps Bernard Picton could help us out on this one - after all he helped describe C. rubescens in 1978 ;-)

Christian Skauge Re-examining my own images of this/similar species. It seems I have two different things... Difficult, and who knows what they look like when they are juvenile? You might be right about C. amoena Brendan - and in that case I may have the first image of this species from Norway :-)

Terry Griffiths Thanks all a new one for me too :-)

Kirstie Harris Terry - stop finding new ones! I have enough trouble finding all the old ones :)

Peter H van Bragt Hi Terry, I doubt that this could be C. rubescens. It lacks the continuous streak of white pigment on the oral tentacles. C. amoena is a fair option. The lack of white pigment spots on the cerata tips, the cnidosac being visible in these tips, white pigment spots on teh abck are indicative. Did you see and photograph any spawn close to this specimen and on what hydroid species did you find it? Could be usefull for the ID.

Christian Skauge I have read the descriptions in all my books now and come to the conclusion that I was probably wrong in suggesting C. rubescens. This means I need to talk to my Norwegian experts... I don't think C. amoena has been recorded in Norway, and we might have misidentified this. Please have a look at this image and tell me what you think: http://www.scubapixel.com/component/content/article/8-images/2437-1021-27032011-7885-Cuthona_rubescens.jpg

Rachel Shucksmith Christian looking at my photographs from Gulen, they look more like C. amoena than C. rubescens, although they are little small for me to photograph well.

Christian Skauge This is quite exciting, actually! I hope I'm wrong ;-)

Terry Griffiths Glad to have helped you out lol.

Christian Skauge ha ha thanks :D

Terry Griffiths Christian get off FB and get back to checking your books .

Rachel Shucksmith On habitas it says: The dorsal surfaces of the oral tentacles have a continuous band of white pigment, and this distinguishing feature is present even in juveniles. Which Terry's, yours Christian on Scuba pixel and mine from Gulen dont have....

Christian Skauge True, htat is one of things I noticed as well. This bugger is more speckled - but could it be a juvenile?

Rachel Shucksmith I do defiantly have C. rubens pics from Gulen as one of my individuals defiantly have the white band all the way along the oral tentacles, my other one is more speckled. They were also on different hydroids.

Christian Skauge Yeah, it seems to be two types.

Bernard Picton Christian, I think yours is C. rubescens. Juveniles of both these species have less pigment than adults, so they do get very difficult to identify at 5mm.

Message posted on NE Atlantic Nudibranchs on 06 May 2013
Kåre Telnes Anyone able to identify this one? From Gulen, the West coast of Norway, this weekend. Water depth 14 meters, approx 15 mm long. F. nobilis?

Richard Yorke I'm no expert, but how about Cuthona rubescens

Steven Melvin Flabellina verrucosa?

Peter H van Bragt the lines of white pigment on the various head tentacles are very much indicative for C. rubescens

Steven Melvin Ah yes I believe you are right. F.verrucosa appears to have more of a white line that runs down the rhinophores, where as C. rubescens it appears more dotted like white pigments

Kåre Telnes Thanks for your replies! Checking my regular sources, I must agree it looks very much like C. rubescens. The only thing is that it seems to lack the red coloration at the base of the cerata, as described by Bernard Picton at http://www.habitas.org.uk/marinelife/ .

Ian Smith Steven Melvin there's an unread offlist message in your messages -click messages in menu on left of this page to see it.

Gary Cobb I think this is Trinchesiaa concinna (Alder & Hancock, 1843)

Terry Griffiths Kare when i left they were still talking about this one and 3 others could be new ones.

Steven Melvin Ian Smith, I do not see any message folders on this page other than my private messages, that has nothing related to this

Bernard Picton This is quite common at Gulen at the moment and Dag Leslie Hansen photographed it in 2010. It is a Eubranchus, quite similar to E. pallidus, but lacking most of the brown spotting. We are not sure if it is a local variant, but typical E. pallidus are here too, so it could be an undescribed species. I'm calling it Eubranchus cf. pallidus.

Kåre Telnes Thanks for the help. I guess I'll not publish the images on www.seawater.no unless anyone at Gulen figures it out. Please, let me know if you do!

Gary Cobb Bernard why do you think this is Eubranchus? This photo has characteristics of Trinchesia concinna.

Bernard Picton Gary, I'm looking at it down a microscope...

Kåre Telnes Did the look in the microscope bring you to any conclusion?

Christian Skauge I think we concluded that this is a variety of Eubranchus pallidus. Bernard came across it mating with a more typical-looking specimen :-)

Bernard Picton Not quite mating, but in compromising circumstances....

Message posted on NE Atlantic Nudibranchs on 12 Mar 2013
Becky Hitchin Can someone confirm (or not) this is Cuthona rubescens? Bad photo, I know. Sorry!

Sarah Bowen No, I don't think so; more likely to be a Eubranchus.

Erling Svensen Agree. Eubranchus pallidus.

Becky Hitchin Drat. I just saw the red line on the rhinophores ...

Matthew Green Fiona Crouch?

João Pedro Silva Best to post this on the NE Nudibranchs group.

Klas Malmberg Aquatilis Eubranchus pallidus most likely

David Kipling Isn't it E. pallidum, the painted one?

David Kipling Pallidus, autocorrect...

Becky Hitchin Must stop trying to ID nudibranchs. I always get them utterly wrong.

Message posted on Seasearch Identifications on 25 Jun 2013
Christian Skauge Still plenty of nudibranchs at the house reef of Gulen Dive Resort, Norway: Cadlina laevis, Cuthona rubescens, Cuthona gymnota, Flabellina nobilis and the illusive Cumanotus beaumonti - to mention a few :-)

Klas Malmberg Aquatilis Fina bilder! Jag längtar dit!!!!!

Arne Kuilman Stunning stuff there. What's the best time to dive there for nudibranchs?

Message posted on NE Atlantic Nudibranchs on 26 Jun 2013
Bjørnar Nygård A small Cuthona rubescens i guess. Found it at 22m depth and in a bit of a current on todays dive.

Message posted on NE Atlantic Nudibranchs on 05 May 2012
Christian Skauge At Bernard Picton's request I'm posting this image of what I thought to be a Cuthona rubescens. He seems to think otherwise, so now I'm a little intrigued... ;-) Photographed at Gulen, Norwegian west coast, March 2010, ca. 22 meters, 1 cm long.

Christian Skauge Are you thinking C. amoena, perhaps?

Bernard Picton I think this could be a different species of Cuthona, perhaps an un-named one. It doesn't have the bold white stripe on the top of the oral tentacles, but white spots and and a brown mark as well, as in Cuthona amoena. The spots on the cerata in white and red-brown are different too.

Message posted on NE Atlantic Nudibranchs on 20 Feb 2012
Antoni López-Arenas Cama Do you think this could be Cuthona amoena or foliata? Found in Mataró (near Barcelona in the Mediterranean Sea) at 18m depth between Posidonia oceanica leaves. Its size was around 1-2 mm. Thank you! http://www.flickr.com/photos/alopezarenas/8672317737/in/photostream

João Pedro Silva Why not C. rubescens?

Antoni López-Arenas Cama why not... why yes? :-) Thanks

João Pedro Silva I'm suggesting this due to the "red pigment at the bases of the cerata": http://www.habitas.org.uk/marinelife/species.asp?item=W14730

Antoni López-Arenas Cama but i don't know if is dark red or brown like Cuthona amoena :-P http://www.habitas.org.uk/marinelife/species.asp?item=W14660

João Pedro Silva You may be right. Plus the rings on the oral tentacles... not an easy one to ID.

Egidio Trainito Cuthona foliata is not considered a mediterranean species (misidentified C.genovae); I think that it is Cuthona amoena, Cuthona granosa is quite different with head body, rhinophores and oral tentacles covered with very fine opaque white. On rhinophores and head tentacles bright orange on the outer parts, look at this: http://opistobranquis.info/en/guia-dopistobranquis/nudibranquis-nudibranchia/eolidacis-aeolidina/cuthona-granosa/

Antoni López-Arenas Cama Egidio Trainito, between Cuthona amoena and Cuthona rubescens, do you think it is clearly amoena? Thank you!

Egidio Trainito C.rubescens is not a mediterranean species, I confirm my opinion: C.amoena.

Peter H van Bragt Peter H van Bragt C. amoena could indeed be a realistic candidate. The dark spot in the head region (oesophagus), granular cerat content and dark rings in both rhinophores and head tentacles is what we also see here in the Netherlands in C, amoena. But its not realy easy to give such a species a name from a photograph of such a small specimen. On what sort of hydroid did you find it??

Bernard Picton It is more like C. amoena than C. rubescens; note the brown mark on the oral tentacles, never present in C. rubescens. It isn't quite the same as any C. amoena I've ever seen, but most species look a little different in the Mediterranean.

Bernard Picton We need to start work on the gordian knots.. http://www.plosone.org/article/authors/info%3Adoi%2F10.1371%2Fjournal.pone.0047214;jsessionid=C7E26F234C576859D205953D222F1F8B

Antoni López-Arenas Cama I think that Cuthona foliata can be a Mediterranean specie. In past some authors misidentified C.genovae as foliata, but this doesn't mean that there aren't Cuthona foliata in Mediterranean sea.

Antoni López-Arenas Cama Here you can see the "Updated checklist of the opisthobranchs from the Catalan coasts": http://www.molluscat.com/SPIRA/PDF/Spira_2_3_5.pdf

Egidio Trainito Previously C.foliata was signaled for Malta but the specimen looked like a very small C.genovae, it would be interesting to see Catalan specimens. Thanks for the useful pdf.

Message posted on NE Atlantic Nudibranchs on 30 Apr 2013
Jim Anderson Is this Trinchesia amoena or Trinchesia rubescens? 5 mm animal with spawn at 12 m in Loch Fyne, Scotland

John de Jong I would go for rubescens based on the red color. http://www.jojodive.nl/Nudy%20branches/Dutch%20%20Sacoglossa%20and%20Nudibranchia/slides/Trinchesia%20rubescens%20.html

Terry Griffiths Thanks for putting this one up Jim Anderson i also managed to get a few photo's of this nudi the other week when i was up there.

Peter H van Bragt Very sure it's T rubescens. cheers Peter H van Bragt

Erling Svensen Silly question: Have this nudi changed name from Cuthona rubescens to Trinchesia rubescens?

Peter H van Bragt Hi Erling. Some years ago there was some consensus among some taxonomists that only Cuthona nana belonged to the Cuthona family and all others should be therefore renamed to Trinchesia. In my publication on Dutch nudi's (2004) the peer reviewers insisted that it should be like that. It seems that now this has changed again and all are back again in the Cuthona family. Trivial names may change often .... scientific names can change too. In Dutch we call this... voortschrijdend inzicht....ny innsikt! Cheers Peter H. van Bragt

Erling Svensen Thanks. I get mad of all these namechanges...

Message posted on NE Atlantic Nudibranchs on 27 Jul 2012
Taxonomy
Animalia (Kingdom)
  Mollusca (Phylum)
    Gastropoda (Class)
      Heterobranchia (Subclass)
        Opisthobranchia (Infraclass)
          Nudibranchia (Order)
            Dexiarchia (Suborder)
              Aeolidida (Infraorder)
                Fionoidea (Superfamily)
                  Tergipedidae (Family)
                    Cuthona (Genus)
                      Cuthona rubescens (Species)
Associated Species