Contacyphon padi

This genus was formerly known as Cyphon and many references have this species listed as Cyphon padi.

Keying this to species was problematic. I initially used Duff and I think I went wrong at couplet 2 which was a choice between the pronotal disc being "evidently finely punctate or microscopically granulate" and "extremely finely, barely discernibly punctate". Each of the hairs on the pronotum emerged from what look to me like small, fine, but readily visible punctures, so I went with the first option. This lead me to a dead-end at the couplet for variabilis and laevipennis, neither of which seemed quite right for a number of reasons. Taking the other route from couplet 2 took me to padi, and this seemed a perfect match against the description, a perfect match for online photos, and it's the most commonly-recorded member of the genus in Norfolk. I then looked at Mike Hackston's key and intriguingly his route to padi demanded "Top of pronotum clearly punctured" as opposed to "with extremely fine punctures which are scarcely visible" (though this was to distinguish from punctipennis which in this respect Duff keys the same way as padi). My specimen was smaller than the size range give in Hackston for padi, but he also stated it was the smallest member of the genus - and Duff gives a lower bottom end which covers mine. Hackston's key also provided a further revelation.

I had examined the genitalia and failed to find anything that I recognised as the aedeagus, but instead had found two pairs of long thin structures which I mistakenly took to be female apodemes. Duff provides illustrations of female prehensors and eight sternites, none of which resembled anything I could find. He also showed the male median lobes which again didn't resemble anything I'd found, and the males' ninth sternites. The latter picture for padi did resemble a structure I found, although being clearly positioned internally I didn't think this was a sternite (at this point I was still quite inexperienced dissecting beetles and hadn't twigged that sternites could be internal like this). Hackston additionally showed diagrams of the eight and ninth tergites for the males and here was the revelation - these were the structures that I had erroneously identified as female apodemes. So it was a male, and the tergites and sternite were a match for padi. I figured I must have lost the median lobe but despite the confusion with the pronotal puncturing I think there's enough to name this confidently as padi. Having since found another male I can well understand my confusion - I had had lots of experience dissecting moths and a bit of experience doing beetles, but mainly species where the aedeagus is a robust and obvious structure (and there haven't been long thin tergites that resemeble female apodomes). I now realise that the aedeagus in this family is a much more delicate structure than I was used to - and indeed comparing my photos of this one with the new one I'm not convinced the aedeagus wasn't there all along...

male Contacyphon padi showing its pronotum (with head and close up), sternite 8 between tergites 8 & 9 (one missing on one side) and a close-up of the tip of sternite 8, Wendling Beck Environment Project (Norfolk, UK), 13th August 2021

A fair amount of time elapsed between me keying the one above and the next one, and I made exactly the same mistake again using Duff's key. The only difference is that this time I didn't see any firm reason to eliniate variabilis until I checked the genitalia (though that "often" has a paler head). For females Duff shows sternite 8 but Hackston's key shows the prehensor and I think this is more distinctive - at least for padi. Comparing what I could see under the microscope against the drawings in Duff made me question my provisional ID of variabilis, but I wasn't convinced I had gone wrong. Just concerned enough to check Hackston, and in doing so it became immediately obvious that I was looking at a prehensor belonging to padi not variabilis.

female Contacyphon padi showing close-ups of head and pronotum (2 angles) and abdominal sclerites/prehensor, Wendling Beck Environment Project (Norfolk, UK), 29th April 2023

This was a darker, more reddish beetle with a much clearer dark mark along the suture and base of the elytra, and based on this pattern alone I was fairly confident it would turn out to be padi. But I'm not sure if this pattern is unique to padi so keyed it out properly (using Duff). Again I wasn't completely sure which way to go regarding the pronotum puncturing but this time it was my favoured option that led to padi. I dissected it very carefully to understand the internal structures better, given my previous confusion, and this both confirmed the ID and helped explain my earlier struggle. The beetle was 2.0mm long and was suctioned from moss in wet woodland.

male Contacyphon padi showing pronotum (2 views) and aedeagus and sternite 9, first in context and then isolated, Wendling Beck Environment Project (Norfolk, UK), 12th March 2025

This was 1.9mm, beaten from Hazel.

male Contacyphon padi showing aedeagus, Wendling Beck Environment Project (Norfolk, UK), 28th March 2025

These were three of four beaten off Sallow. I recognised some of them as probably being padi but initially assumed the black ones with just a pair of orange spots on the apex of the elytra were something different. Keying them took me to padi though, and a quick check of online images confirmed that this colour form is not unusual.

male Contacyphon padi showing hind tarsus and aedeagus, Wendling Beck Environment Project (Norfolk, UK), 4th April 2025

second male Contacyphon padi showing genitalia, Wendling Beck Environment Project (Norfolk, UK), 4th April 2025

third male Contacyphon padi showing aedeagus, Wendling Beck Environment Project (Norfolk, UK), 4th April 2025