Tachinus subterraneus

This was found in my garden moth trap and was identified in 2023 using Mike Hackston's keys. This was the first of 3 Tachinus that I examined and I wish I'd first looked at one of the others which still had the long sensory bristles on each side of the abdomen in place, as it took me a while to work out what these were. They'd broken off, though with the benefit of hindsight I see they were still attached when I took the photos of the live insect. Part of the problem is that Hackston refers to them as being on the side of the tergites, but says that if they have broken off the corresponding punctures can be seen on the sternites. I could indeed see a puncture on the 5th exposed sternite (but not the 3rd and 4th), but I wasn't entirely sure if this was what it meant. I could also see some fine erect hairs on the upper surface of the tergites, one in the centre of ecah segment which couldn't be what was being referred to but also a pair towards the sides - probably not close enough to the side to count, but I wasn't certain. There also seemed to be an equivalent bristle on the very sides of the sternites which pointed upwards. Could these have been what it meant? In the end I moved on from here assuming it was the big puncture on the 5th exposed sternite side that was being referred to, as otherwise it would have to be Tachinus lignorum and other characters weren't quite right for that. When I later viewed a different Tachinus which still had the bristles in situ I realised that these are way bigger than the little hairs I was musing over.

This had tormentum patches on the first three exposed tergites (in death at least these were not exposed beyond the elytra - I had to remove these and the wings to view them). The punctures on the pronotum were obviosuly smaller than those on the elytra and the pronotum had a clear border along the front edge.

The specimen was female and neither Hackston nor the German website coleonet.de show the 8th tergite for this species, although this is evidently important for the ID of several other Tachinus species. Also neither show the spermatheca for any Tachinus so I've no idea if this can be helpful or not. So I've not been able to confirm the ID using these, but include photos so this can be done in future if either prove to be helpful (somewhere down the line I got confused as to whether I was looking for the 8th sternite or the 8th tergite and then wondered if I had mixed them up - I've included photos of both just in case but I think the tergite is shown first).

female Tachinus subterraneus showing front border of pronotum, pronotal punctures, elytra (2 views), tomentum patches, abdomen hairs on tergites viewed from side, puncture on 5th exposed sternite, 8th tergite, 8th sternite and spermatheca, North Elmham (Norfolk, UK), 8th December 2016