What's in the box? no.3 - a new species!

OK, a little different this time - instead of a beetle arriving by post, this one was handed to me in person during the 8th Coleopterists' Day which took place yesterday at the HQ of the British Entomological & Natural History Society (BENHS) at Dinton Pastures Country Park in Berkshire, southern England.

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...

It was found on a sun-baked hillside in southern England while beating hazel (Corylus) back in June. All fine so far, except that despite the keying out, it doesn't look right for S. affinis - the main reason is the lack of a dark longitudinal stripe on the pronotum which, as far as I am aware is always present in this species. There were four other specimens in the BENHS collection (being collected in the early 20th century they were under the old generic name, Gynandrophthalma) and they all matched each other but varied from my specimen. Hmmm... it definitely looks like Smaragdina, but this genus only has one known species in Britain; could this be something really very interesting? So, having brought it home, it was time to have another look in the next morning.

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.

It's still a bit tricky (the two species are not massively different even at this level of detail), but the aedeagus does look like that of S. salicina; this species also has the antennal colouration mentioned above while S. flavicollis has more orange antennae on the whole. S. salicina is known from a range of trees, shrubs and other plants, so being found on or near hazel is fine for this species.

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.