Trechus quadristriatus

The North Elmham records below came to light in my garden.

I found this one easier to key using Duff than Hackston, having tried the latter first. I'd misinterpreted the pronotum shape at Hackston's couplet 3 as the hind angle was more obvious than in the diagram, although in hindsight the rest of the couplet probably should have led me the other way. Arriving at a pair of species that were too big (as well as unlikely in North Elmham) I realised my error. Duff differentiated on size early on which saved some of the headache, and I also found his diagrams at the start of the Trechus key helpful. One of the confusing things I found was that at some angles the second stria seems to end abruptly at a bristle after curving away from the suture (exactly as shown in Duff's diagram) but at other angles it can be seen that this stria continues to the recurved sutural stria (curving back towards the suture, or at least so that it's parallel to the suture again).

Trechus quadristriatus showing tip of elytra (3 angles), pronotum (2 angles) and mentum and palps, North Elmham (Norfolk, UK), 10th August 2023

2x Trechus quadristriatus showing tip of elytra of first and position of rear bristle by eye of second, North Elmham (Norfolk, UK), 11th August 2023

Trechus quadristriatus showing positions of apical bristle-bearing puncture on the third stria and rear bristle by the eye, North Elmham (Norfolk, UK), 12th September 2022

Trechus quadristriatus showing positions of apical bristle-bearing puncture on the third stria and rear bristle by the eye, North Elmham (Norfolk, UK), 24th September 2021

2x Trechus quadristriatus showing positions of apical bristle-bearing puncture on the third stria and rear bristle by the eye, North Elmham (Norfolk, UK), 21st August 2017 (first photo is one individual, others are the second individual)

Trechus quadristriatus, North Elmham (Norfolk, UK), 12th September 2022

Trechus quadristriatus, North Elmham (Norfolk, UK), 23rd August 2017

Trechus quadristriatus, North Elmham (Norfolk, UK), 27th August 2019

These two were caught in a pitfall trap.

2x Trechus quadristriatus showing positions of apical bristle-bearing puncture on the third stria and rear bristle by the eye, Wendling Beck Environment Project (Norfolk, UK), 29th October to 2nd November 2022 (first photo is one individual, others are the second individual)

Trechus quadristriatus, Wendling Beck Environment Project (Norfolk, UK), 1st March 2023

Trechus quadristriatus, North Elmham (Norfolk, UK), 15th August 2023