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Onchidoris muricata

(O. F. Müller, 1776)


Erling Svensen Onchidoris muricata - very tiny one.....

Message posted on NE Atlantic Nudibranchs on 06 Feb 2013
Cat Wilding Can anyone help with an ID for this nudi please? Adalaria proxima or Onchidoris muricata? Neither of these have been recorded near the site before. From ~8m in mid-Fowey estuary, on a pontoon. This is the best photo I have in which the tubercles appear quite rounded, suggesting O. muricata? Cheers!

George Brown Have you considered Onchidoris bilamellata? The remains of many barnacles appear close by.

Ross Bullimore Yup... + 1 ..what George Brown said!

Fiona Crouch Yep that would be my first thought George and Ross.

Peter H van Bragt And indeed it is O. bilamellata.

Cat Wilding Awesome, thank you :)

Message posted on Seasearch Identifications on 28 Oct 2013
George Brown Is this Onchidoris muricata and Gibbula cineraria? The Onchidoris is about 8mm long. What should I be looking for? North Strome, Loch Carron. 5 metres depth. 2013-10-13.

Simon Taylor I'd say yes to both George, though I'm more qualified to comment on the Gibbula. The shape of the shell and frequency of coloured rays confirm that one.

George Brown Thank you Simon, Ian and Becky.

Message posted on British Marine Mollusca on 22 Oct 2013
Paula Lightfoot I think this is either Onchidoris muricata or Adalaria proxima but not sure if it's possible to tell from this photo? From Eyemouth.

Rob Spray Not easy to tell but using Bernard's ID advice from Habitas I would say flat tubercles... so prob O.Muricata? http://www.habitas.org.uk/marinelife/species.asp?item=W13240

Brendan Oonk Based on the discription of Adalaria proxima on sea slug forum "Very similar in shape, colour variation, food and habitat to Onchidoris muricata. It grows to a larger size (17-25mm - compared to 12mm for O. muricata), and the mantle papillae taper to a slender rounded tip while in O. muricata they are flattened with projecting spicules." I would say: O. muricata

Ian Smith I read somewhere that radula examination is necessary to separate them, but in the 70's when I sent material from Orkney to Thompson & Brown, my prediction of species based on tubercle shape was always confirmed when radulae were examined. It would help if the image were cropped in tighter, but I think I can see mainly flattish topped tubercles, so I agree with Rob in saying muricata. Also, in the south muricata is usually (but not always) white and proxima yellowish (colours reversed in Orkney). T&B suggest that proxima doesn't come south of Bristol Channel, and records to the south are misident. of muricata; two more factors that add to the probability of your specimen being muricata. You can see tubercle comparison on the Conch Soc A.proxima page at http://www.conchsoc.org/spaccount/Adalaria-proxima there is a link to the muricata page on it too. Note that the comparison images are from Orkney so proxima white, muricata yellow. Cheers Ian

Message posted on NE Atlantic Nudibranchs on 30 Sep 2012
Erling Svensen Have anybody seen the Onchidoris muricata with this kind of colour before? (I hope it is O. muricata?)

David Kipling What is the blue and orange thing in the bottom left corner Erling?

Jussi Evertsen The purlpe and orange colors are the stomach contents shining though the animal - this varies depending on what ectoprocts it has been feeding on

Erling Svensen I do not know, David. I have the high res. picture, and I have been looking. It is so strange. May be an alien? ;-)

Bernard Picton I think this might be a juvenile Archidoris pseudoargus. The tubercles are too numerous and the rhinophores the wrong shape for Onchidoris.

João Pedro Silva Just a few days ago Cláudio Brandão posted a photo with a purple tinged Archidoris/Doris pseudoargus: https://www.facebook.com/photo.php?fbid=373832925982153&set=o.166655096779112&type=3&theater

Bernard Picton Now we can have a debate about whether to call them Doris, João. I'm against unnecessary name changes by creating huge genera at the present time when we know the phylogeny can be worked out using DNA in a few years... At that time we'll be able to name clades more objectively.

João Pedro Silva I agree with the principle (like the Cuthona/Trinchesia "issue"), Bernard, although I'm not qualified to get into that debate :)

Message posted on NE Atlantic Nudibranchs on 28 Mar 2012
Nils Aukan Nudibranchs,Onchidoris muricata on a sea-squirt+Cuthona viridis on a hydroide,Kristiansund-Norway,30.01-2013

Message posted on UWphotographers on 01 Feb 2013
Paula Lightfoot I think this is either Onchidoris muricata or Adalaria proxima but not sure if it's possible to tell from this photo? From Eyemouth.

Rob Spray Not easy to tell but using Bernard's ID advice from Habitas I would say flat tubercles... so prob O.Muricata? http://www.habitas.org.uk/marinelife/species.asp?item=W13240

Brendan Oonk Based on the discription of Adalaria proxima on sea slug forum "Very similar in shape, colour variation, food and habitat to Onchidoris muricata. It grows to a larger size (17-25mm - compared to 12mm for O. muricata), and the mantle papillae taper to a slender rounded tip while in O. muricata they are flattened with projecting spicules." I would say: O. muricata

Ian Smith I read somewhere that radula examination is necessary to separate them, but in the 70's when I sent material from Orkney to Thompson & Brown, my prediction of species based on tubercle shape was always confirmed when radulae were examined. It would help if the image were cropped in tighter, but I think I can see mainly flattish topped tubercles, so I agree with Rob in saying muricata. Also, in the south muricata is usually (but not always) white and proxima yellowish (colours reversed in Orkney). T&B suggest that proxima doesn't come south of Bristol Channel, and records to the south are misident. of muricata; two more factors that add to the probability of your specimen being muricata. You can see tubercle comparison on the Conch Soc A.proxima page at http://www.conchsoc.org/spaccount/Adalaria-proxima there is a link to the muricata page on it too. Note that the comparison images are from Orkney so proxima white, muricata yellow. Cheers Ian

Message posted on NE Atlantic Nudibranchs on 30 Sep 2012
David Fenwick Snr Another curious yellow slug, thankfully not Berthella this time. Haven't a clue what it is despite doing a lot of looking. Has anyone come across it ?

David Fenwick Snr It's about 12mm and found under a rock in a pool at Lariggan Rocks, Penzance, Cornwall. 06.04.12.

Steve Trewhella Onchidoris muricata ?

David Kipling There have been a few records of Doris ocelligera from the Penzance area. That can come in a yellow form with dark tips to the tubercles (which you seem to have here). Only a handful of UK records to date, it's on the northernmost limits of its range.

David Kipling See here in particular Julia Nunn's picture of the yellow variant. http://www.seaslugforum.net/showall/doriocel

David Fenwick Snr Thanks David that's the beast, flatter than O. muricata, white tubercules, and larger tubercules in the centre getting smaller round the edges and with like you say dark tips to the tubercules. Brilliant. It just didn't fit in with O. muricata or Adalaria proxima, know I know why. Just as your mail came in I grey scaled the images and increased brightness and contrast to see what it would look like being white. It still didn't look like O. muricata, I think what stands out the most is that the slug is flatter than O. muricata and the tubercules are larger down the center, O. muricata seem to be quite uniform and equal sized. Thanks David

David Kipling Do re-post to NEAN, it's a good find!

David Kipling Jim Anderson has a good selection of (Scottish) O muricata here, which show those even-shaped tubercles all the way to the edge. http://www.nudibranch.org/Scottish%20Nudibranchs/onchidoris-muricata.html

David Kipling The other key thing are those dark spots that make the tubercles look like little chimneys. And as you say, the tubercles get smaller near the edge.

David Fenwick Snr Just been to http://www.seaslugforum.net/showall/doriocel and read about all the Cornish records. Glad to see there's a Mounts Bay record for the species. Will sent the info on and make sure your records also go on the ERICA database; the species doesn't currently feature. Thanks David

David Kipling There is another Penzance record; in (?) 2009 Matt Swardlow of Buglife was rummaging around in the rockpools under the Jubilee swimming pool on the seafront and found one. It got a mention in Simon Barnes' column in the Times (Aug 22 2009) under the heading 'Dirty Doris'. Text of the article is copied below. "Dirty Doris Biodiversity is one of the great resources of a nation, or a planet, and it is to be celebrated in its endless forms most beautiful. So I called Matt Shardlow at the invertebrate charity, Buglife, to ask what I had seen on the Cornish cliffs. It looked, I said, like an ichneumon wasp. It was, he told me, an ichneumon wasp, so I was delighted with myself. It was slender, long-bodied, with a rather floaty flight and a ginger band round what we entomologists call the bum. The ichneumons are a large group: this was a species of Netelia, and I am the richer for knowing this. But Matt himself had done rather better on his own Cornish jaunt. He had, he told me, found Doris ocelligera in a rockpool. This is a sea slug 2cm long, and it is only the third time that one has been found in this country. It is rare throughout its range, a dirty white thing with dirty white lumps that have dark tips. And no one has any idea at all what it eats. Isn’t that all strangely and quietly wonderful? There’s beauty everywhere, if you care to look. Good idea not to destroy it, in my view." (reposted from http://www.timesonline.co.uk/tol/comment/columnists/simon_barnes/article6805779.ece)

David Kipling I hope Jan Light is listening to this, she wrote up the original sightings for Mollusc World.

David Kipling Matt's record is useful as it confirms you can find this critter in rockpools (which is where you found it David?). Ie it's not a just deep-water critter.

David Kipling If confirmed, yours is only the fifth ever sighting in the UK (AFAIK). Bernard Picton will probably want you to pickle it!

David Fenwick Snr Sadly we put them back, we found two under the same rock, they were in a small middleshore pool on the west side of the rocks at Lariggan Rocks. Can look for them again if Bernard wants to see them.

David Kipling It would be interesting to know what else is under that rock. The shape of the nudi makes it look like a sponge, with those little chimneys looking like oscules. The information I can find suggests that it is a sponge-eating Dorid, with suggested foods including Halichondria, Haliclona and Hymeniacidon, based on this review: http://www.theveliger.org/nudibranch_food.html Any encrusting sponges under those rocks?

David Fenwick Snr I think we'd best have a look for some more !!!

David Kipling You took this specimen from Lariggan Rocks in Penzance. This is 1km along the coast from the outdoor swimming pool where Matt Shardlow from Buglife made his 2009 rockpool sighting of this species. Add to that our own sighting (at 25m deep on a wreck about 1km south of this point in the bay) then it sounds like you have got a stable(ish) local population of this species in Mount's Bay.

David Fenwick Snr We regularly go to Chimney Rocks (west of swimming pool) and haven't seen it there yet, but we'll keep a good eye out for it now though, and also at other sites as across the bay.

Bernard Picton David Fenwick, this is a really exciting find. I've never seen one, but it does look as though it is now well-established on the south coast there. Julia Nunn, found more than one (mentioned above). There are no old records at all from this far north, so a good candidate for climate change spread.

Joshua Hallas i was wondering if anyone lives or frequents the Isle of Man

Sarah Bowen No, but I know someone who does now live there. He's a keen Seasearch diver; don't think he does FB though so isn't on here. Any particular reason?

Bernard Picton Christine did the 3rd year of her degree course at the marine station in Port Erin. Unfortunately Liverpool University have closed the station, but I'd have contacts on the island...

Joshua Hallas I'm looking for any and all onchidorids from that area, specifically Onchidoris pusilla. The radula of a potentially new species is extremely similar to O. pusilla. So DNA and anatomy is important for me to verify that what i have is different from O. pusilla. I know that Miller was able to find lots of O. pusilla back in the 50's and right now its towards the end of their spawing time. So if your contacts Sarah Bowen and Bernard Picton are able to help me out that would mean a lot.

Bernard Picton Miller collected most of his specimens by dredging I think, looking on dead bivalve shells and other substrata with encrusting bryozoa. I do have some Bouin's fixed specimens of O. pusilla I think, but have not seen it for years. The best place to look is under stones and rocks, which divers don't usually do.

Joshua Hallas if you end up finding those Bouin's fixed O. pusilla i would love to see them because than the radual and the reproductive system would be able to looked.....

Bernard Picton OK, Josh, I got some Onchidoris muricata and Adalaria proxima into ethanol for you last week, so I'll send a package.

Joshua Hallas thanks a lot, hopefully O. pusilla might shine a light on the black onchidorid from scotland

Message posted on NE Atlantic Nudibranchs on 25 Mar 2012
Taxonomy
Animalia (Kingdom)
  Mollusca (Phylum)
    Gastropoda (Class)
      Heterobranchia (Subclass)
        Opisthobranchia (Infraclass)
          Nudibranchia (Order)
            Euctenidiacea (Suborder)
              Doridacea (Infraorder)
                Onchidoridoidea (Superfamily)
                  Onchidorididae (Family)
                    Onchidoris (Genus)
                      Onchidoris muricata (Species)
Associated Species