Another thing was I knew it was going to be tricky before I even saw it - the person handing it over is an experienced coleopterist who knows his beetles, so if he can't ID it... Anyhow, being at the BENHS did mean that I had access to books and microscopes there and then, plus some other coleopterists to ask. So, starting at the start, it was about 5mm long, with blue-black elytra and head, an uptilted tip to the scutellum, orange-red pronotum, orange legs (apart from a small dark bit near the base) and dark (with an orange part near the base), fairly short antennae with triangular segments giving a somewhat serrated appearance. OK, that looks like, and keys out as, Smaragdina affinis - one of the leaf beetles (Chrysomelidae) and a rare one considered Endangered (RDB1) in Britain.
|The mystery Smaragdina...|
There are other Smaragdina species in Europe - could one have found its way here, or been overlooked? Looking through the European species online and in books, I came to two possibilities - found not too far away in Europe, and broadly the right colour etc.- S. flavicollis and S. salicina. Looking at how to separate them, they are very similar - although varying in average length, the size ranges overlap and this specimen sits right in the middle of the overlap, so that's no guide. Also, both can have a hairless vertex to the head with a shallow round dent (which this does). So, off to the dissecting microscope.
|Head on - a tricky little beast.|
|Head showing round depression on the vertex between the eyes.|
Fortunately it's a male, so I could dissect out the aedeagus and compare it to those of the two possible species I'd come up with.
|Aedeagus showing somewhat spatulate end, blunt 'pimple' at the tip, and other structures.|
So, do I have a species new to Britain? Well, it's not on the most recent British list and I don't know of any publications reporting it having been found here - still, finds like this need checking to make sure.
* UPDATE * My ID has been verified by an expert - it is S. salicina which is widespread in continental Europe, including France, so it is plausible that this is a genuine new species to Britain, either overlooked or recently arrived. Next step - try to work out whether it's established/breeding (and can go on the British list) or whether it is a one-off 'import'. More info when I know!
* UPDATE 2 * This has now been published as a paper:
Hubble, D. & Murray, D. (2011). First British record of Smaragdina salicina (Scopoli, 1763) (Chrysomelidae). The Coleopterist 20(1): 1-3.