Two species are included in Joy's Quedionuchus :
cinctus Pk. and laevigatus Gyll. These are now included in the genus Quedius Stephens.
Quedius cinctus is the only member of the subgenus Distichalius Casey,
and Q.plagiatus Mann. (=laevigatus Gyll in Joy) is the only member of the subgenus Quedionuchus
Both species are distinct with a series of three large punctures on the anterior half of the pronotum, head and pronotum black and abdomen black with the apical margin of the tergites narrowly yellow, eyes large, occupying a little more than half the side of the head, and elytra with a row, or several rows, of larger punctures between the shoulder and the suture.
Quedius cinctus (Pk.) is featured.
In Q.plagiatus (6-8mm) the elytra are dull and entirely red with a single series of often indistinct punctures on the disc, the basal three or four antennal segments are yellow and the palps are red. This is a mostly Scottish species, rare in the north of England, occurring under the bark of fir logs (joy).
A further species, which may cause confusion, has been added to the British list since the publication of Joy's handbook; Astrapaeus ulmi (Rossi) will key to Quedionuchus in Joy but will correspond to neither species. It is larger, 10-15mm, with shiny red elytra which have a single series of four or five shallow punctures between the shoulder and the suture. The pronotum is shiny and unpunctured, and the appendages are black but for the two basal antennal segments which are reddish yellow. Several specimens have been found in East Sussex (Hance, 2007)
Hance, D.2007. Astrapaeus ulmi in Britain. Coleopterist 16(1):1-2