Tachyporus nitidulus
This was in a pitfall trap (in propylene glycol, so no live photos). I recognised it as being Tachyporinae and keyed it using Hackston, arriving at this species smoothly and quickly. It was only a little over 2mm long.
Tachyporus nitidulus showing maxillary palp, tarsi, and elytra, Wendling Beck Environment Project (Norfolk, UK), 29th to 31st March 2024
This was in the same pitfall trap. It was a bit bigger (around 2.6-2.7mm) and not as dark, but it's meant to be a variable species. I stuggled to see the detail of the elytral suture and punctures to decide which way to go at Hackston's first couplet in the Tachyporinae key so tried both options. One option led to a dead end and the other led to this species.
second Tachyporus nitidulus showing elytra (2 views), labial and maxillary palps and hind tarsus, Wendling Beck Environment Project (Norfolk, UK), 29th to 31st March 2024