Chiton septemvalvis

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.

Paula Lightfoot Is this a Doto sp? Sorry terrible quality photo!

Christian Skauge Yes, Doto ;-)

Steve Wilkinson And Callochiton (septemvalvis) :)

Christian Skauge And a barnacle :)

David Kipling I see no-one is guessing the sponge species though ...

Paula Lightfoot Sponge?! There is encrusting pink algae, and no I'm not guessing which species. There were white tortoiseshell limpets Tectura virginea on the pink algae too.

Julia Nunn yes Doto sp. with a Callochiton septemvalvis (chiton) next to it

Christian Skauge The pink algae might be Phymatolithon sp. - but I am NOT an expert on this ;-)

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.