Philonthus quisquiliarius

I initially used Hackston to key these but could only get as far as Philonthus sp. Then I obtained the Lott & Anderson and finished the job. It wasn't an easy ID - I didn't find it easy to determine whether tarsal and antennal segments were transverse or elongate - the difference didn't seem to be vast. Perhaps a bigger problem was at the couplet where I had to choose between black femora (corvinus) or pale brown femora (quisquiliarius and ventralis). They weren't black, though the front femora weren't very far off, but pale brown? I wouldn't come close to describing them as pale. Then deciding how faint the microsculpure was proved tricky without any reference material. But going through the descriptions of all three species and comparing images in the book and online I'm fairly confident they were quisquiliarius - and this is much the commoner of the three species and in the right habitat (well, just up from the right habitat - it came to light in a grassy field just above a wet meadow, along with heaps of other insects that must have come up from the wet meadow like water boatmen, caddisflies and mayflies). Both were female so I wasn't able to compare aedeagi with the diagrams in the book.

female Philonthus quisquiliarius showing front and hind tarsi, pronotal punctures and microsculpture, Wendling Beck Environment Project (Norfolk, UK), 11th June 2023

second female Philonthus quisquiliarius showing front and hind tarsi, pronotal punctures and head microsculpture, Wendling Beck Environment Project (Norfolk, UK), 11th June 2023

This one turned up in my moth trap at home. I keyed it to quisquiliarius before dissecting it to check the genitalia. Fortunately this time it was a male and so I was able to confirm the ID, and in doing so increased my confidence that I was keying the last two correctly. I think I must have damaged this specimen when re-potting it after its photoshoot as the specimen had its head damaged and twisted half-off the pronotum, but fortunately this damage didn't mask any of the features needed when keying it.

male Philonthus quisquiliarius showing head (2 views), palps, antenna, pronotum (5 views, the last two showing the side border from the side and from above), hind tarsus and aedeagus, North Elmham (Norfolk, UK), 24th June 2023