Adrastus pallens

One of the key characters supposedly distinguishing this species from Adrastus rachifer (which I think would be very unlikely in Norfolk) is the relative lengths of the second and third antennal segments. On pallens they're meant to be "about equal" whereas on rachifer the second is clearly shorter. I examined the two 2021 records below together and to my eye the second segment was noticeably shorter than the third. I measured them, and it was a little over 10% shorter. So had I found Norfolk's first (and second) rachifer? I don't think so. One was about 4.4mm so longer than the stated range for rachifer, and the other was noticeably bigger still. Moreover, Mike Hackston's key provides an additional character not mentioned by Duff which is that segment four onwards are sharply toothed vs. roundly toothed in pallens. These were roundly toothed.

All of my records so far have come to light in my garden.

Adrastus pallens, North Elmham (Norfolk, UK), 19th July 2021

Adrastus pallens, North Elmham (Norfolk, UK), 19th June 2021

Adrastus pallens, North Elmham (Norfolk, UK), 25th July 2019

Adrastus pallens, North Elmham (Norfolk, UK), 12th June 2017

Adrastus pallens, North Elmham (Norfolk, UK), 18th July 2019