Beetle with bi-coloured antenae

Bruce Williams · #1 (**permalink**) 07-03-2010, 10:26 AM

Stony Stratford, Bucks. On fence beneath broadleaf trees near large pond.

Help with identification appreciated:

Bruce

Jason Green · #2 (**permalink**) 07-03-2010, 12:46 PM

Afternoon Bruce,

It's a Ground Beetle from the Carabidae family. It reminds me of an Amara sp., but there are quite a few unfortunately with orange-basal antennae. Someone else should be along soon to help.

Take care,

Jason

Bruce Williams · #3 (**permalink**) 07-03-2010, 03:31 PM

Thanks Jason

.

Now that's a pity, I'd thought the antennae would be fairly helpful in identifying it to species

.

Bruce

Dogghound · #4 (**permalink**) 07-03-2010, 04:44 PM

Almost certain its Amara aenea. Hard from a photo, as Jason says a few Amara have these Pale antenna base although the said species is the most commonly found.

Paul mabbott · #5 (**permalink**) 07-03-2010, 05:05 PM

Yes, good picture of an Amara - any indication of size? I think we may even be able to key this one out ..... maybe ....

Bruce Williams · #6 (**permalink**) 07-03-2010, 07:45 PM

Dan and Paul - Thanks for your help with this one.

Size is a confident 9.75mm

Bruce

ladyhawk · #7 (**permalink**) 08-03-2010, 12:35 AM

if it had a sort of greenish tinge as well i tend to agree its Amara aenea.

Bruce Williams · #8 (**permalink**) 08-03-2010, 07:00 AM

Thanks ladyhawk - Well I've looked at all the pics I took of this beetle and can't say that any of them show a noticeable green tint....

Bruce

Paul mabbott · #9 (**permalink**) 08-03-2010, 08:09 AM

Quote:

Originally Posted by ladyhawk

if it had a sort of greenish tinge as well i tend to agree its Amara aenea.

Aeneous is sometimes defined as 'greenish-gold' but more commonly 'brassy' or 'like bronze'. While in some cases such as Harpalus affinis (formerly Harpalus aeneus) the colour is distinctly greenish, in most cases it is the golden sheen which is distinctive...... as in this case.

Paul mabbott · #10 (**permalink**) 08-03-2010, 08:17 AM

Okay, I've had the regulation two cups of coffee: I also think it's Amara aenea although that measurment is a tad too long (shouldn't exceed 9mms)!
The critical features are absence of a scutellar pit (i.e. no little hole at the end of the small central striations below the pronotum; no external depressions on the pronotum; three pale antennal segments; small slits towards the middle of the pronotum; slight golden sheen.
The only real confusion could be with Amara convexior but that is smaller, without golden hue, with more curved elytral intervals and tends to be more southern in UK. Good picture.