Malthodes marginatus

I was unable to make out the shape of the genital segment clearly on this one so cleared it in potassium hydroxide solution for a better view.

male Malthodes marginatus showing genital segment (before and after clearing), North Elmham (Norfolk, UK), 17th May 2020

2x male Malthodes marginatus showing frons and genital segments, Wendling Beck Environment Project (Norfolk, UK), 26th May 2023

male Malthodes marginatus showing genital segment, Whitwell Common (Norfolk, UK), 14th May 2017

male Malthodes marginatus, Thursfood Wood (Norfolk, UK), 22nd May 2017

Duff states that only males can be reliably identified but goes on to include females in his key. However this refers to the shape of sternite 9 but he doesn't provide any diagrams and I wasn't entirely sure if I could identify which sternite 9 was. I'm assuming it was one of the internal plates as I could only count 6 external sternites, the last of which had a large rounded notch. Stretching out the internal workings I couldn't identify anything that clearly matched the description of sternite 9 for any species. Duff also refers to the relative length of the elytra and Hackston also includes a provisional key for females which uses this. Based on the elytral dimensions this female appears to be marginatus - which of course is no surprise as this is the commonest species and the only one I've seen that looks like this externally.

female Malthodes marginatus showing side of pronotum, apical sternites (2 views before extraction and one with internal sclerites pulled out) and elytral measurements, Beetley Meadows (Norfolk, UK), 28th April 2025