The sap is rising

Now that I'm putting the moth trap out again given the warmer temperatures, there's a bit more opportunity for some nighttime perambulations in the garden. Beetles are still thin on the ground from direct searching and I have to get the sieves and suction sampler out to find decent numbers.

Whilst out at the weekend, I remembered to check a field maple where I had to remove a low branch earlier in the winter. I had a look back in November/December and not found much but when I took a peek this time there were a fair few small beetles feeding on the sap that was rising out and congealing in the night air.

 

They were obviously nitulids and I was pretty sure in the genus Epuraea. That's one of those genera that makes my head hurt so I took some back with me for further study.

My initial hunch was right. Epuraea was spot on. They keyed the species pair E. unicolor/biguttata, which can only be reliably separated on differences in male genitalia. So I did what had to be done.

Comparing these to the diagrams in Duff vol 3, I reckoned I was looking at E. unicolor, which was a new species for me, having seen biguttata before. I decided to seek out some more info which is when things got confusing...

I couldn't find any information. It isn't the latest checklist except as an invalid name for biguttata and searches weren't turning up anything. I then remembered to check the Coleopterist search and I found an article from 2020 by Roger Booth showing the existence of two species unicolor and biguttata, both widespread. 

So now I gained a species and then lost one, as I'm not sure I can rule out my previous biguttata actually being unicolor. Bugger.

So note to self to dissect all these as a matter of course from now on.