Cercyon laminatus

This is meant to be quite a scarce species and as such I'm a bit annoyed with myself for not keeping better records of how it was identified (or the specimen). It was after I'd acquired the relevant Duff volume so I think I would have used this, probably alongside Hackston.

Cercyon laminatus, Wendling Beck Environment Project (Norfolk, UK), 25th September 2021

My annoyance at the last one dissipated when I caught another nearby, again to light, this time LED lights. This time I initially used Duff to key it. My only hesitation in calling it laminatus was that the eyes did not seem especially large to me, and they were hardly protuberant at all. I turned to Hackston and found that he used a very different set of criteria, but I still ended up at laminatus - except again that I was unconvinced by the size of the eyes. A search of online images of all Cercyon species came up with a small number of insects that looked like mine and every one of these was labelled laminatus, so this upped my confidence, but my mind was finally made up when I checked if coleo.net had images of the genitalia. It does, and the aedeagus in flat view was a good match for mine (in side profile theirs was slightly more sinuous but very base of mine seems to be missing (broken?) so I think that might explain the discrepancy in that view). Although it's a relatively scarcely recorded species several references mention that it comes to light - I generally find that those beetle species documented as ones that readily come to light are species that I record relatively often compared to the overall number of records, and I assume that is because relatively few coleopterists regularly use light-trapping as a means of finding beetles.

male Cercyon laminatus, Wendling Beck Environment Project (Norfolk, UK), 26th August 2024

This was 3.2mm long. I initially used the Hackston key to identify it but went wrong, ending up at Cercyon lateralis but with some concerns. So I checked the ID using Duff. This time I went wrong again - looking back at my notes I think I must have omitted to key it to subgenus and started at subgenus Cercyon. I can see from the photo that the metasternal field was very narrow - indeed my notes even say that I would call it a keel rather than a field, which had I used the subgenus key would have got me straight to subgenus Paracycreon in which the only species is laminatus.

It was unfortunate that my mistakes in both keys both led me to the same wrong species, so even though I had misgivings using both keys I figured it must be lateralis. Duff doesn't show the genitalia for these, and at the time I examined it neither did Hackston. However I did check the genitalia and photograph the aedeagus just in case it might help in future.

I'm very grateful to Mike Hackston for picking up on my mistake and advising me to revisit it. He's also added some diagrams of the aedeagus to his keys and he pointed out that of the Cercyon aedeagi shown at coleonet.de is the only one showing the aedeagus significantly longer than the parameres is laminatus.

Cercyon laminatus showing evenly-curved side-profile, pronotal base/corner, mesosternal field, metasternum, elytron and aedeagus (3 views), Wendling Beck Environment Project (Norfolk, UK), 21st August 2023