What's in the box? No.7 - loadsa leaf-beetles and an interloper

As promised, I'm back to my pet theme - beetles - in particular, the mysterious specimens that arrive by post because I coordinate the UK's Chrysomelid Recording Scheme which covers what are commonly known as leaf, reed, seed, tortoise & flea beetles (i.e. the Chrysomelidae, Bruchinae, Donaciinae, Zeugophorinae, Megalopodidae, Cassidinae and Orsodacnidae). So, now you are sufficiently overloaded with taxonomic terms (not to mention the fact that whether or not some are considered families or subfamilies varies by book/website), let's have a look at what prompted me to start writing...

What arrived in the post...

Usually I get a single specimen tube with one or two beetles in, but not this time... What I have here is an old Kodak slide-box full of about 20 little envelopes, each of which has several beetles of different species in. The envelopes are neatly labelled (date, location, UK grid reference) and the beetles look to be in pretty good condition. Also, the sender did get in touch first (and included return postage so he can have the specimens back once identified) so I expected more than the usual number of specimens. Most will be 'flea beetles' (subfamilies Galerucinae & Alticinae) as they are the ones the sender couldn't identify himself, and these are the ones most likely to be problematic (even to specialists on occasion). They also represent the parts of my test key which are receiving the most comprehensive rewrite as some of the keys to these genera didn't work well enough. So, although it will take a long time (it looks like there are about 100-200 beetles), it's really useful to have some unknown specimens to work through while I rewrite the relevant keys, as well as providing useful data for the recording scheme. It will also give me plenty to blog about... so, on to the first envelope!

A closer look at the contents of the first envelope.

Here it is clear that two of the beetles are larger (around 8mm long) and less smooth and shiny. These are reed beetles (subfamily Donaciinae) and will be the subject of a separate post soon. The one that stands out - to me anyway - is the small black roundish one more-or-less in the middle of the group.

A close-up of that round blackish beetle.

This beetle is around 3mm long and although shiny, you can see tiny punctures on the surface of the wing-cases (elytra). However, this isn't what grabbed my attention - it's the leg sticking out, in particular the pair of spurs at the joint of the femur and tibia. This gives me a good idea of what this beetle is, but let's turn it over to make sure.

Ventral view showing the enlarged hind femurs

Close-up of the enlarged hind femur. Personally I like the detail of small hairs in this photo.

The large femurs enable this beetle to jump and similar structures are seen in the 'flea beetles' within the family Chrysomelidae. However, flea beetles don't tend to be this round, nor do they have leg-spurs quite like those seen here; also, although you can't see the detail here, some fine details of the structure of the head are different from the chrysomelids. In fact, this isn't a chrysomelid at all - it is Scirtes hemisphaericus which is in the family Scirtidae and, as noted by Cooter & Barclay (2006), is sometimes confused with the flea beetles because of its legs and jumping ability. It's also in a family that is relatively unfamiliar, possibly because there is no modern book covering the British Scirtidae; however, the key in Joy (1932) still works well (although it was then called the Helodidae) and is available on a CD-ROM which is rather more affordable than the original 2-volume book (as it happens, I have the 1976 reprint which wasn't too expensive as collectors don't like ex-library books because of the stamps and marks - personally I don't care as long as it's complete).

I intend to continue this series, especially as I should have no shortage of material, interspersed with other ecological musings. In this case, I've started the 'mystery chrysomelid' thread with something that isn't a chrysomelid at all - I wonder what will appear next...

References

Cooter, J. & Barclay, M.V.L. (eds.) (2006). A Coleopterist's Handbook (4th ed.). Amateur Entomologists' Society, Orpington. An absolute must for beetle enthusiasts! Based on the UK beetle fauna.
Joy, N.H. (1932). A Practical Handbook of British Beetles (2 vols.) (1976 reprint). Classey, Farringdon.