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Tonicella marmorea

(Fabricius O., 1780)

Rudolf Svensen Anybody know this chiton? It was at least 50 mm long and the largest I've ever seen. Only one I can think of is Tonicella marmorea. Image captured at 30 meters depth in a fjord on the South-West coast of Norway.

Vasco Ferreira That big and deep i can only occur Chaetopleura.

Erling Svensen Acanthochitona fascicularis grows to 6 cm, but I do not know if it has been recordet at the norwegian coast yet?

Steve Wilkinson Rudolf - this is really interesting photo. It is definitely not Tonicella. The closest species is Acanthochitona fascicularis except that the the shape of the valves looks odd and the tufts of bristles are very obscure (if you look really carefully there is some evidence there). I had previously questioned records of this species in Norway and having seen this I think it needs a little more follow up. Will let you know how I get on. If it is possible to get a high res copy of this image that would be really useful I would quite like to look at the sculpture on the valves.(see http://www.conchsoc.org/spAccount/acanthochitona-fascicularis)

Rudolf Svensen Hi Steve Wilkinson I can send you some high res images if you want. Just give me Your e-mail address. I got one person who identified it as Hanleya hanleyi it is a close relative to Hanleya nagelfar which is also found in this area. The last one lives on and inside geodia sponges.

Steve Wilkinson Hi Rudolf thanks for the images - really useful. Definitely not Hanleya for all sorts of reasons. But also quite different to A. fascicularis from elsewhere. Will do a bit more digging and let you know. Also did you spot the little chiton just to the left of the shot? Probably Leptochiton asellus I imagine but cant be sure even off the high res images.

Steve Wilkinson Have had a bit more of a look at the images and conferred with John Baxter who wrote the Linn. Soc. guide covering the UK species. We think it is H. nagelfar (we dont get that species here). Your friend there ruled this out - and I would be interested in why. H. hanleyi is smaller and has a much narrower girdle. There does seem to be some dispute as to whether H.n. is just a big H.h. While Kaas' monograph recognises the two species he concludes "So the last word on Scandanavian Hanleya species has not yet been spoken." Would make quite an interesting genetic study if we had a few animals.

Rudolf Svensen Hi Steve Wilkinson. If i find some more I can collect them and send them to you. Cannot promisse anything though, but I'll do my best to find them :-)

Message posted on Seasearch Identifications on 21 Mar 2013
Paula Lightfoot Hi - I think this is Lepidochitona cinerea, but someone else is saying they think it's Callochiton septemvalvis so any help would be appreciated! It was about 3cm long on the middle shore in Scarborough. I think its L cinerea because the girdle is relatively narrow, banded and has a granular surface and obvious fringe of spines - whereas C septemvalvis would have a wider girdle wouldn't it? To be fair, the other person has the actual specimen so may well be seeing features not visible in my photos. I have recorded C septemvalvis near Scarborough but only on a dive.

Jan Light I'm not an expert but at that size I would say it is Tonicella marmorea. See what others say....

Ian Smith I don't know, but the following may help decide. Measure its length accurately. As Jan says, if 30mm, it's too big for cinereus (max 19mm), ok for septemvalvis, just ( 30mm max) and marmorea, likely (40mm). The only one of the three spp. that usually can be found on mid shore is cinereus. If now dead, extract the end plate at the head end and count the number of notches; marmorea 8-10, cinereus 8, septemvalvis 15-20. If still alive, place on glass in sea water. When attached, turn over. On cinereus and septemvalvis the gills on either side of foot run almost whole length of animal (holobranch). Marmorea can be holobranch to merobranch (gills only part of body length). If merobranch and under 20mm, other possibilities. Paula do you have a copy of Gillian Matthew's useful little "paper for students" on chitons?

Paula Lightfoot No I don't - that sounds like it would be useful! I'm afraid I don't have the specimen and 30mm was my estimate from seeing it on the shore - I will ask for more info on the specimen (now dead!).

Ian Smith Hmm! Just looked at conch soc website http://www.conchsoc.org/spAccount/lepidochitona-cinerea my image but not my text. Says cinerea max 28mm (may be extracted from Linnean synopsis which is most up -to-date comprehensive account - I don't have it). Hayward and Ryland say 24mm. G. Matthews 19mm is probably the most frequent max, with the other measurements extreme examples, but possible.

Julia Nunn absolutely not Callochiton septemvalvis. Looks like Tonicella marmorea from the markings on the girdle; and the way the granularity is on the plates. However, specimen would be best of course

Steve Wilkinson I think you were right first time Paula. Lep cin does get big and can be green (big might indicate paracitised by Minchinia chitonis which might ad another species to you r list :)). Callochiton would have a snake skin girdle and not banded like this. Tonicella would be pretty much completely smooth - both valves and girdle. These valves (the younger bit anyway) are sculptured as you would expect with Lep cin. Also I have never seen Tonicella mid shore.

Simon Taylor Doesn't look right for Callochiton to me but also doesn't have the look of Lepidochitona either. It's really impossible to do chitons like this properly without a good look at the specimen through a lens or ideally down a microscope.

Simon Taylor Nice photos by the way - can we use one as the group photo for a while?

Paula Lightfoot Sure you can use one of those Simon or this one which I think is prettier :) Big spring tides this weekend, I'm supposed to be leading rocky shore wildlife events for local groups but I think I'm just going to be obsessively looking for chitons to try and identify ;)

Julia Nunn this one really does look like Lepidochitona - and a beautiful picture

Simon Taylor Yes that's a lovely specimen and shows the sculpture on the plates and girdle nicely too.

Message posted on British Marine Mollusca on 27 Sep 2013
Dave Rolfe Unknown Chiton from Skye, about 7mm long. Marmorea?

Jan Light Not sure. Chitons not my strength. Person who might help is Steve Wilkinson but he is not in this group I think. Perhaps Simon could invite him?

Julia Nunn Tonicella marmoreal I am almost certain

Julia Nunn marmorea*

Dave Rolfe As I thought, thanks Julia.

Steve Wilkinson Sorry only just joined and skimming through. Do you remember whether this was from the beach or what sort of height/depth. To be honest it looks more like the ubiquitous Lep cin to me....

Jan Light It also has some resemblance to Callochiton septemvalvis, the colouration is typical. The girdle of Callochiton is very distinctive though, the spicules lying flat in a snake skin pattern. Possibly not possible to resolve if you do not have the specimen. Lep cin girdles are normally banded, not very clear in the photo here.

Dave Rolfe Steve, it was on the beach, between tide marks.

Message posted on British Marine Mollusca on 06 Aug 2013
Animalia (Kingdom)
  Mollusca (Phylum)
    Polyplacophora (Class)
      Neoloricata (Subclass)
        Chitonida (Order)
          Acanthochitonina (Suborder)
            Mopalioidea (Superfamily)
              Mopaliidae (Family)
                Mopaliinae (Subfamily)
                  Tonicella (Genus)
                    Tonicella marmorea (Species)
Associated Species