Olibrus corticalis
This is the Olibrus I've encountered most often, despite Olibrus aeneus (which so far I've never found) being more common and widespread in Norfolk.
Olibrus corticalis, North Elmham Cathedral Meadows (Norfolk, UK), 12th May 2021
The nipple-shaped final segment of the antenna is distinctive to all members of this genus. Here you can also see how the second sutural striae meet the first before the apex. This individual was identified by this and the microsculpture on the pronotum, but the identification was confirmed by checking the genitalia.
male Olibrus corticalis showing tip of elytra and antennal club, North Elmham (Norfolk, UK), 6th May 2022
On this one the second sutural striae didn't quite meet the first sutural striae.
female Olibrus corticalis showing tip of elytra, pronotal microsculpure, elytral microsculpture and ovipostor, Buxton Heath (Norfolk, UK), 23rd April 2021
In the two photos of the genitalia below, the left hand aedeagus belonged to beetle in the first photo and the right hand aedeagus belonged to the beetle in the second photo.
2x male Olibrus corticalis showing aedeagi (flat and side views), North Elmham Cathedral Meadows (Norfolk, UK), 21st February 2021
The nipple-shaped antennae and the pronotal microsculpture were noted on this one, but not photographed.
Olibrus corticalis showing sutural striae, North Elmham (Norfolk, UK), 11th April 2024
male Olibrus corticalis, North Elmham Cathedral Meadows (Norfolk, UK), 1st March 2019
2x male Olibrus corticalis, North Elmham Cathedral Meadows (Norfolk, UK), 13th February 2019
Olibrus corticalis, North Elmham Cathedral Meadows (Norfolk, UK), 25th March 2020
Olibrus corticalis, North Elmham Cathedral Meadows (Norfolk, UK), 8th March 2020
female Olibrus corticalis, North Elmham Cathedral Meadows (Norfolk, UK), 17th February 2019
Olibrus corticalis, North Elmham Cathedral Meadows (Norfolk, UK), 12th August 2018
Olibrus corticalis, Beetley Common (Norfolk, UK), 12th March 2017