What's in the box? Two of one, one of another (part 1)

While at the annual Coleopterists' Day at the Oxford Uni Museum of Natural History last weekend, I was handed a small wooden box with three pinned beetles in it. If you are an entomologist, this will be familiar as specimen-swapping is an important way of seeing varied specimens and passing on tricky beasties to specialists for identification. Not that getting a box of beetles was the real reason I was there - there's a really good entomology library to rummage through plus I gave this talk to my fellow beetle-nerds, now published in a slightly more formal version as Hubble (2013).

Box of beetles - two Aphthona on the left, and a larger Oulema.

So, to the beetles - they'd all been tentatively identified, but were passed to me for confirmation. I started with the larger one, 'a female, probably Oulema melanopus'.

Pinned female Oulema - note the blue-black head and elytra and red pronotum.

The female genitalia had been dissected and preserved in a drop of clear mountant. The important part is the little knot bottom-right where 'sd' = spermathecal duct.

An extract from Cox (1995) comparing the female genitalia of O. melanopus and O. rufocyanea, two very closely related species.

Looking at the images in Cox (1995), and the equivalent in Hubble (2012), it is clear that Figure 6 is close to the specimen here, including the short spermathecal duct and arrangement of other tubules. So, this is O. melanopus - good practice at a sometimes-tricky species group aided by some excellent dissection (not mine!). This may be even more useful given that unpublished and ongoing Swiss work on specimens of O. melanopus has shown that a small number of them turn out to actually be O. duftschmidi. There's no indication that this latter species exists in the UK, but it has a Western Palaearctic distribution so it's not impossible and I'll be keeping an eye out...


References

Cox, M.L. (1995). Identification of the Oulema 'melanopus' species group (Chrysomelidae). The Coleopterist 4(2): 33-36.
Hubble, D. (2012). Keys to the adults of seed and leaf beetles of Britain and Ireland. FSC, Telford.
Hubble, D. (2013). Progress report on the Chrysomelidae recording scheme. The Coleopterist 22(3): 103-109.