Simplocaria semistriata

This was a pig to identify, not helped by it not conforming to the typical appearance for this species. The main challenge was getting to the right family - and staying there once I had. I used both the Unwin and Duff family keys and struggled with both. To be fair, both did get to Byrrhidae, but in both keys there were choices that weren't altogether convincing. When I did get to Byrrhidae I initially used the Hackston key to that family and ended up with Simplocaria semistriatus, with a photo of a beetle that was even less elongated than mine and virtually black. After trying various other families that I got to if I went with different choices at the less clear couplets I got nowhere. In desperation I tried ObsIdentify and Google Lens. The former was useless and the latter threw up a number of vaguely similar beetles in a variety of other families that I hadn't checked. Each one was looked up, but none were right. Finally I pawed through all the illustrations at the end of Duff until I came to something similar. There was nothing, but I kept my thumb in one page which had the only vaguely similar beetle which had a similar antennal structure. It was Simplocaria semistriatus again, but it was still black, and the description in Duff confirmed "Body black with a slight bronzy lustre". I ran it through Duff's key to Byrrhidae and it did very neatly arrive at Simplocaria semistriata - but there was no allowance for brown individuals with patches of paler hairs.

The UK Beetles website also described this species as "body black with a variable metallic green or bluish-green metallic reflection". I had by this time at least concluded that Simplocaria semistriata wasn't always as squat as the one in Hackston's key, so that wasn't a problem - it was just the colour. My next step was googling Simplocaria to see if I could find anything similar, and I could - it was a photo of Simplocaria maculosa on boldsystems.org. It ws the right colour and it even had the pale patches. Could mine be maculosa (and a first for Norfolk I think)? Surely the hairs on mine were far too long and sticking out too much, and the pronotum had clear microsculpture between the punctures, so no, I didn't think so. Duff said maculosa should be the same colour as semistriata, so if that could have a pale form not noted by Duff then maybe so could semistriata? Eventually I found a photo of semistriata that was brown, though darker and redder-brown than mine and lacking any pale patches. I was pretty sure now, but still with a niggling doubt that I was even in the right family I checked its genitalia, desperately hoping it would be a male. Phew, it was, and it matched semistriata perfectly. Mystery finally resolved. It was 3.0mm long, so at the upper end of the size range for this species.

One final thought on this - could the brown colour be because this was teneral? I imagine teneral individuals don't stay brown for long and as this was still brown when it died so I'm guessing not, but then again it didn't survive long in its pot so maybe?

male Simplocaria semistriata showing elytral hairs, pronotal microsculpture and aedeagus (with close ups focusing on tip of median lobe and parameres), Wendling Beck Environment Project, (Norfolk, UK), 23rd May 2023