Lower eulittoral area, having to look hard for these guys.
No interactions present.
A tough one Graham. Should it not be a lot flatter ('compressed' in my book)?
See this one http://www.ispot.org.uk/node/284614
Note your stress line too - I'm interested in those.
An excellent FSC Treatise here, which I have just discovered.
...is the umbilicus - hence Chris's agreement (I guess)?
Original 20 May 2013
Edit one word, not changed the meaning.
Yes, the giveaway, sorry.
I am on the case and will investigate 'mine' more closely here. I think then far more 'umbilicalised' than I'd thought (maybe!).
Is this not the Grey Top Shell Gibbula cineraria?
A few things here. Graham will reassert that the umbilicus makes it clear; and Chris doesn't make 'mistakes' very often (if at all!).
But like you Cathal, I was doubtful at first. I was to post my own until I realised it is NOT as straightforward as colour, shape, even umbilicus (which both have).
So, well done for asking - neat!
You won't have to wait long...you see..
You've both got me here! & I think http://www.discoverlife.org/mp/20q?search=Gibbula shows well the different Gibbula species, eg G. cineraria with similar sized holes to this
Hi Chris and Derek,
They seem to be very different in colouration in both MarLIN and in your link Chris. If I am not missing some relevant info they appear readily seperable?
I need someone to explain what the umbilicis is please? In complete ignorance of what the feature is, these just seem like 2 quite differently marked species ansd the above matches cineraria.
The umbilicis must be the central hole, right?
G. umbilicalis is also refered to as the Flat Top Shell, the first picture above shows a high peak from the side, much higher than G. umbilicalis and spot on for cineraria.
I have agreed - but I am away from home so cannot be completely convinced until I use my own resource.
But I will say, well done for the challenge Cathal.
I was intrigued by what you had commented earlier about the colouration not being reliable for seperating these species. It made me wonder had I formerly been wrongly IDing cineraria but all the reference pics of both species show the same colouration and marking differences. I cant see any 'in betweeners'?
I agree they do look markedly different Cathal
(& umbilicus in humans is the belly button)
Thanks Chris for the belly button reminder. I just couldnt recall why the word was familiar before I googled it.
On another note, is Topshell better than Top Shell? I prefer the former but Marlin had it as 2 words and I let that influence me.
If I have seen umilicalis it has been on very few occasions, I see cineraria a lot. When I saw the broad purple bars of umbilicalis coming up on iSpot from time to time, it just seemed so markedly different from the one I was used to (cineraria) as you say. Its more decorated and colourful.
Yes, all three of us have been through this before - see the comment-trail here http://www.ispotnature.org/node/324592
I remain unconvinced they are easy to separate unless they are both to hand.
Of all the features Flatness (low profile) seems the most useful as I feel colour may be, sometimes, misleading.
Topshell, in my opinion, is correct but iSpot dictionary does not accept it (preferring Top shell), so one would have to complete the Latin name by hand, as it were. I don't remember doing that but had an aversion, in my earler days, to relying on iSpot Suggested Names (which you must have done Cathal).
It's a confused and confusing issue on the Web and also in iSpot itself - seach for Topshell!
Searching for Gibbula umbilicalis - proves how difficult this short group is - not many agreements!
Cathal you may have missed my Hotlink (umbilicus) in Away (which I will be until about 7th Feb).
where the umbilicus is clearly not present - so still inclined to think this is the purple, colour is no guide as has been already stated.The barring on the shell also seems to be wider than cineraria.
If you have a look at this link which Chris posted above, you can see that cineraria has a large umbilicus. Both species have it.
The umbilicus on your shell matches those in the linked pictures of cineraria in that it is more elongated/oval shaped than on the other Gibbula.
As far as I can see there is a marked difference in the appearance and shape of G. cineraria and G. umbilicalis. Mature cineraria are much taller than mature umbilicalis. The fine barring seems to be a feature of cineraria only.
The barring on your shell is perfect for cineraria and much too fine for umbilicalis. It is also tall in spire which is consistent with mature cineraria.
The necessary pictures are in this webpage:-
Regarding the lack of umbilicus in the linked observation of cineraria in your comment, I think it is there and I think I can see part of it beyond the pincer of the hermit crab which largely obscures it. A straight on view would clear that up, the angle in the shot is just right for it to be hidden behind the crab nipper.
Yes,I agree with Cathal. Graham's other Grey Top Shell is clearly Gibbula cineraria, which is why I agreed early. But what is not clear-cut in any of this, is colour and umbilicus - they seem variable, each possessing elements of the other, though banner-pattern (as Chris remarks and maybe why he has shifted his agreements here) may be the best separator.
I don't think G.umbilicalis occurs frequently in Orkney and I don't yet think I have found one.
So Graham, your challenge, should you wish to accept it, is to photogrpah them side b side (a few views), tagging your post Marine so we, the infamous five, can see!
I do not have any of my lovely resource to hand (away from home) but when I do, I'll make more sense, honest!
These topshell goings-on induced me to look for them at Rhossili &, unlike you Cathal, found the flat rock platform littered with umbilicus (as many as there were winkles) & only 1 or 2 cineraria [with criterion umbilicus has Broader & less zigzag banner-pattern]. But when dry they're almost as grey as winkles).
Lat/Lng: 51.3835, 1.3233
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