Anobium inexspectatum

This beetle is very similar to the Common Furniture Beetle Anobium punctatum but unlike that species isn't likely to damage your antique furniture. They are best identified by checking the male genitalia.

male Anobium inexspectatum showing its genitalia (flat and side), North Elmham Cathedral Meadows (Norfolk, UK), 24th September 2021

According to Duff, punctatum shows lateral longitudinal impressions on the metasternum, lacking on inexspectatum. I'm not sure exactly what these are meant to look like but when I examined the following mating pair of Anobium I saw that each side of the metasternum had a faint line (I couldn't quite tell if it was an impression or a shallow ridge), running inexactly parallel to the sides. I was therefore half-expecting them to turn out to be punctatum, however the male's genitalia were clearly inexspectatum.

male Anobium inexspectatum showing both sides of its metasternum and its genitalia, North Elmham Cathedral Meadows (Norfolk, UK), 24th September 2021

I'm not sure how safely females can be identified but this one was found in copulation with the male above, so I presume it is the same species. In this case the male was noticeably darker/blacker than the more reddish-brown female, but as the first male shown at the top of this page was equally reddish I assume this isn't a consistent sex-related difference.

female Anobium inexspectatum, North Elmham Cathedral Meadows (Norfolk, UK), 24th September 2021

Duff and Hackston describe differences in the antennae of the two species with inexspectatum having segments 4-8 "weakly serrate" (Duff) or "rather angular on their inner surface" (Hackston). Worth noting that you have to examine them at just the right angle to see this - see my two photos below which were taken with only a slight adjustment to the angle.

male Anobium inexspectatum showing both sides of its metasternum and its genitalia, North Elmham Cathedral Meadows (Norfolk, UK), 24th September 2021

This one was a female and at the time I was not happy to put a name to it. I've had both inexspectatum and punctatum at the location so both are possible.

unidentified female Anobium sp., North Elmham Cathedral Meadows (Norfolk, UK), 31st July 2021