Ophonus puncticeps

This is a difficult genus to identify. I've experienced some challenges and have now re-identified one individual which I originally showed on this page, albeit laden with caveats as I was aware there were some problems with calling it puncticeps. I now think it was rufibarbis, having compared the specimen with one each of what I think are puncticeps and rufibarbis. I have caught a few Ophonus which I've had to leave unidentified and mostly when I've checked the genitalia they've turned out to be females (for which I'm unaware of any genitalic differences between the species).

One of the challenges for me in identifying the genus comes in interpreting the pronotum shape. Duff says rufibarbis/schaubergerianus etc. have, "Pronotum wider, as wide as the elytra at the humeri" vs. puncticeps, "Pronotum narrower, almost quadrate and usually clearly narrower than the elytra at the humeri". Well, that sounds simpler than it is in practice, at least for me. I'm assuming when it refers to pronotum width it means the maximum width of the pronotum, not the width at the base where it's adjacent to the elytra - but is that right? Having looked at a bunch of photos of both species I'm not convinced I can make out the differences.

This one was examined at the same time as two which I eventually identified as rufibarbis. Like those, it was a female so I couldn't confirm the ID with reference to the genitalia, but I am fairly confident. There was only one (long) bristle protruding from the side of the pronotum (4 on the rufibarbis).

female Ophonus puncticeps showing side of pronotum, North Elmham (Norfolk, UK), 14th August 2021

I re-examined another puncticeps I examined at the same time but this unfortunately lost its label so I'm not entirely certain which one it was though I think it was one of two Ophonus I caught in July 2018 (one of which I put down as puncticeps and the other I left unidentified).

This one was swept in an area where there was lots of Wild Carrot - puncticeps is apparently often found on Wild Carrot.

Ophonus puncticeps, Cranwich Camp (Norfolk, UK), 17th July 2021

So it proves that like so many things, these turn out to be a little easier with experience. This one was identified as puncticeps much more quickly than the previous ones. Happily this one was a male and so gave me an oppportunity to confirm the ID with reference to the aedeagus.

male Ophonus puncticeps showing top of head, base of pronotum and base of elytra, pronotum and aedeagus (flat, side, close-up of tip from side and close-up of cornuti), North Elmham (Norfolk, UK), 2nd August 2024

On an exceptional night for beetles (over 240 comprising 18 species), this male turned up in my moth trap with 2 Ophion rufibarbis.

male Ophonus puncticeps showing side bristle of pronotum, prontoum with base of elytra and aedeagus (flat, side, close-up of tip from side), North Elmham (Norfolk, UK), 12th August 2024

Here is the last beetle flanked on either side by the two female Ophonus rufibarbis caught with it. Note that the puncticeps in the middle is slightly further back than the two rufibarbis - it was not shorter (at least barely so - they were all almost exactly the same length). You can see the difference in pronotum shape here - it looks noticeably smaller (especially narrower) on the puncticeps.

male Ophonus puncticeps (centre) between 2 female Ophion rufibarbis, North Elmham (Norfolk, UK), 12th August 2024

I had been almost prepared to give up on this one had it been another female, and looking back at it after some further experience with the genus (see above) I think I probably should have done anyway as I identified it as rufibarbis which in the light of further experience of the genus I now thing was incorrect. The pronotum was clearly more sparingly punctate in the centre than at the edges as in rufibarbis, but the contrast was less clear than on some. The innermost elytral interval had 4 rows of punctures in some places. I thought I'd eliminated puncticeps on the pronotum shape, but I couldn't see as many lateral trichobothria on the pronotum as usual for rufibarbis/schaubergerianus. The specimen had gone a bit yukky and needed a heavy clean so I figured this may have displaced some of the trichobothria.

The shape of the aedeagus clearly eliminated schaubergerianus and looked fine for rufibarbis, but Duff doesn't include a diagram for puncticeps. Hackston does, but the differences are not very clear. At the time I thought it was enough to confirm this as rufibarbis, but looking at it again in the light of experience with male puncticeps (and catching both species together) I started to question whether I could really see what the differences in the aedeagus are, especially in side view which is all I photographed here. It looks like puncticeps may be more asymmetrical in flat view, but unfortunately I didn't manage to get a photo of this one at that angle. Now looking at Käfer Europas I see the whole aedeagus is illustrated in side view for both species and there do appear to be differences which weren't clear from looking at the diagrams in Duff and Hackston. There may be a subtle difference in shape but a much more obvious difference in the diagrams is the arrangement of cornuti, with rufibarbis containing smaller patches, particularly the patch in the distal half which is illustrated as being very extensive in punticeps (taking up more than a quarter of the length of the aedeagus) and very much tinier in rufibarbis. My subsequent experience of puncticeps conforms with that illustration but I'm yet to see a photo of a cleared rufibarbis aedeagus (there's a photo of one at the same website but not cleared so you can't see the cornuti at all). I can't see any difference in my photos of the aedeagus of this beetle I originally identified as rufibarbis and the two male puncticeps that I've seen subsequently (above), or the illustration of puncticeps at Käfer Europas. If it is puncticeps then that explains why I couldn't see any more than one lateral trichobothria, and it explains why the discal pronotal punctures were stronger than they tend to be in rufibarbis, a difference which is now clearer to me having examined more rufibarbis alongisde puncticeps.

male Ophonus puncticeps showing pronotum, centre of elytra and aedeagus from side (whole and close-up of tip), North Elmham (Norfolk, UK), 13th August 2023