Unknown Beetle

[Suzanne B]

I saw this little beetle when I was digging up my allotment. It seemed to be in the dirt but could just as easily have fallen off something into my path.
I can't find an id in my book even though it looks so distinctive.
It was about the same size as a ladybird and was very fast hence the blur.




Thanks
Suzanne

[Pudding4brains]

Hi Suzanne,

I think Sphaeridium lunatum looks quite similar, but I'm sure there'll be 20 lookalikes or so As always: I'm no good with Beetles anyway, so this is not an ID and I will probably be corrected on this before too long.

Cheers, Arp

[paul m]

Originally Posted by Pudding4brains

........I think Sphaeridium lunatum looks quite similar, but I'm sure there'll be 20 lookalikes or so ......... Cheers, Arp

Yes, that's the nearest I see yet - but I don't know what the competition is either!

[Pudding4brains]

If we limit the competition to the genus it seems there would be 4 in Britain (Fauna Europaea - I seem to have misplaced Pauls link for the British checklist ). Of these marginata can be excluded I would think, leaving bipustulatum and scarabaeoides as extra candidates (all in cattle dung).

• S. lunatum 5,5-7,5mm/4,3-7,0mm? apical pale spot not prolonged along side margins (Images: eb, wcg, dlia)
• S. bipustulatum 3,5-5,5 mm/3,5-5,2mm? (Images: eb, wcg, dlia)
• S. scarabaeoides 5-7.5mm/circa 6mm? (Images: eb, wcg)

That's all I have time for now ... follow the links to "dlia" for some more characters.

NOTE: All info from random internet sites - reliability questionable!!

Do you have any, even blurry, more lateral images?

Cheers, Arp

[Suzanne B]

Thanks Arp and Paul, very interesting information there.
I found a slightly sharper photo although it's in much the same position as the first unfortunately.



Suzanne

ps best when you click on it twice.

[Pudding4brains]

Hi Suzanne,

Hmmm, I've looked at it a few times now, trying to match the ID-ing characters I could find for these and I really shouldn't pretend that I've got a clue

I'm fairly confident it will indeed be a Sphaeridium however, so personally I would keep it at Sphaeridium sp. (Coleoptera: Hydrophilidae).

In the gallery Paul mentioned he has a book on these, so maybe if he stumbles on it he can do better than that, but I'm a tad worried these will prove to be basically IDable "hands-on" only, or with a range of good shots from many different angles.

Sorry, Arp

[Suzanne B]

Hi Arp
Having looked at the images of Sphaeridium sp. as you suggest it does look very similar to all examples so I think I shall agree with you and leave it at that.
For such a distinctive little thing there doesn't seem to be a lot of info easily available (and by that I mean easily available in my little book.) so
I was just wondering if these are common or not as this is the first one I've come across.

Anyhow, thanks for your help it is much appreciated.

[Pudding4brains]

Hi Suzanne,

I should keep quiet as I don't know the first thing about these beetles or their status, but as these are "aquatic" beetles that have adapted to living or if you will "swimming" in wet, fresh cattle dung two thoughts spring to mind:

1 - They must be (or have been) under recorded as it's not everyone's hobby to sift through fresh cattle dung looking for wildlife and hence they would mostly only been seen by humans when trying to get from a drying patch of dung tho fresher pastures.

2 - In the advent of bio-industry, with less and less cattle ever seeing the light of day and all their poo being neatly "managed" I have little doubt that these must have a very hard time surviving abundantly, if at all.

But both ideas are highly speculative (!) I don't actually know things about (those) beetles.

Cheers, Arp

[Suzanne B]

Hi Arp

They are very interesting observations you make and ones I hadn't thought about myself even though they both make perfect sense.
I think I may do a little research on the subject myself now just to see if I can find out anything more about these little beetles.

Thanks
Suzanne

[paul m]

I still haven't found my keys (on CD not paper, I think) but have come across one that I saw earlier - some quite clear features on this photo?

[Pudding4brains]

Hi Paul,

Nice I'm having problems applying all the characters I found (mostly here) - such as "punctation fine, dense.""(?), but if the "apical pale spot not prolonged along side margins" is truly diagnostic this would indeed be lunatum

Cheers, Arp