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Acanthochitona fascicularis

(Linnaeus, 1767)

Rob Durrant Acanthochitona crinitis or Acanthochitona fascicularis?

Steve Wilkinson Hi Rob not sure if you can you zoom in any more. The key feature you are looking for is the patterns on the valves and specifically the shape of the these - tear drops or circular.From what I can see here I would say A. crinita (tear drop / oval) but it is one of those than needs a really good photo. Also girdle doesnt really look wide enough for A.fasc.

Rob Durrant Thanks very much, Steve. I will post a closer view from an image that seems a bit clearer. I was focused on getting the bristles.

Ian Smith Agree with Steve, A. crinita (can see oval granules if click on image).

Rob Durrant Many thanks, Ian Smith.

Julia Nunn agree crinita

Message posted on British Marine Mollusca on 23 Oct 2013
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
Animalia (Kingdom)
  Mollusca (Phylum)
    Polyplacophora (Class)
      Neoloricata (Subclass)
        Chitonida (Order)
          Acanthochitonina (Suborder)
            Cryptoplacoidea (Superfamily)
              Acanthochitonidae (Family)
                Acanthochitona (Genus)
                  Acanthochitona fascicularis (Species)
Associated Species