Olibrus liquidus

male Olibrus liquidus showing its aedeagus (side views and 2 flat views showing both parts in focus), North Elmham Cathedral Meadows (Norfolk, UK), 24th August 2020

According to my notes the genitalia were checked on this one too, though I don't have any photos to prove it.

male Olibrus liquidus, North Elmham Cathedral Meadows (Norfolk, UK), 5th September 2020

This one was a female. The reticulation on the elytra was pretty obvious.

female Olibrus liquidus showing antenna and elytral microsculpture (2 views), Wendling Beck Environment Project, 17th July 2024

These two were found by suction sampling, in the same field as the one above. The male threw me slightly as the sutural striae didn't unite, making the first couplet in Duff's Olibrus key hard to call. But Duff does say they "usually" unite implying that they don't always, and it didn't seem black enough for the alternative option. I checked the latter just in case and it keyed that way to aeneus (which despite apparently being the commonest member of the genus has so far eluded me), but this didn't seem right. The alternative led to liquidus although the elytral reticulation wasn't nearly as obvious as it was on the individual above. Fortunately the aedeagus left no room for doubt.

male Olibrus liquidus showing elytral apex (2 views), elytral microsculpture and aedeagus (flat view, median lobe only flaty and side views), Wendling Beck Environment Project, 4th March 2025

female Olibrus liquidus showing elytral apex and ovipostor gonocoxa, Wendling Beck Environment Project, 4th March 2025

These were also found by suction, in the same field. I found it hard to see the microsculpture on the elytra and as such they keyed to flavicornis. However that species is supposed to have entirely black upperparts so this did not seem right. I suspected they were in fact liquidus and the aedeagus confirmed (although on the first one I managed to break it in half during my attempt to remove the abdomen and that made it slightly uncertain, but the second was straightforward).

male Olibrus liquidus showing prosternum and metasternum, Wendling Beck Environment Project, 17th April 2025

second male Olibrus liquidus showing aedeagus, Wendling Beck Environment Project, 17th April 2025