Hypera venusta

I found identifying both of these a challenge, and both specimens have been retained in case anyone wants to check them and in the hope that I will be able to compare them to similar species in due course.

The main challenges for me in identifying the first one were assessing the degree of how bifid the scales are. On venusta the scales are incised almost to the tip whereas on postica they are less deeply bifid, incised to about two thirds. Well the problem here is that there is a mixture - most are incised to near the tip but quite a few (especially some of the paler most prominent scales) are only incised to about two thirds. Then if we go with the majority, we hit a further problem. The next couplet depends on the pronotal disc having bifid scales in the midline or not (nigrirostris does, venusta doesn't). Where Mike Hackston's key diverges on this character he does allow for "occasionally a few [incised scales] are present" on the choice that leads to venusta, but Duff is clear-cut. The vast majority of scales along the midline of my individual's pronotal disc are simple, but at least 2-3 are slightly incised. If we follow the incised route we end up with nigrirostris, but Duff says this has bright green elytral scales so this is clearly wrong - or is it? Hackston refers to a brown form of nigritrosis, so could it be this? There are various other Hypera species, but I think I have eliminated all of these, so now I'm left with a choice of venusta, postica and possibly a brown nigrirostris.

I am eliminating nigrirostris based on the fact that it seems this is normally green, so the odds of me finding a brown one where I'm yet to find a green one seem rather small. Moreover most of the photos I've found of brown ones have some green scales, and in any case they don't really look anything like my example. I have subsequently found nigrirostris and this had obviously incised scales all the way down the midline of the pronotum, so any niggling doubt that it might have been this species are eliminated. Photos of postica show quite a distinctive apperance, with some sources suggesting that the species is quite easily identified from this appearance. It does vary a little though, and I am not sure that mine is definitely out of range for it. However, photos of venusta look extremely similar to my example, so as that's where the key ends up if I base it on the majority of scales then so long as it's a common species and the habitat/foodplant is right, I'm happy with that. And therein lies another problem. Of the three, venusta is the least common and the only one for which the listed foodplants don't grow in the field where I swept it. However, one of its foodplants (Gorse) grows very nearby and there is a caveat "rarely on other Fabaceae" - so I think this is maybe not too much of a problem. I also note that the individual featured at the eakringbirds website was recorded from an area containing much Red Clover, which is also abundant where I recorded this.

apparent Hypera venusta showing some of its elytral scales (two photos) and its pronotal disc scales, North Elmham Cathedral Meadows (Norfolk, UK), 31st July 2021

On the next one (which came to light) my main issue at first was ruling out Hypera meles. Duff separates this from venusta etc. by it having two dorsolateral furrows on the rostrum above and parallel with the scrobes. On close inspection there seemed to be shallow furrows here, which I tentatively took to be what Duff was referring to. For extra reassurance I checked the high quality images of this species online by Mark Gurney, and I couldn't see anything there that were more clearly furrow-like than what I was seeing. That briefly upped my confidence that it was meles, but then I noticed that his equivalent photo of Hypera venusta was, as far as I could tell, exactly the same. Maybe it's just one of those features that doesn't photograph well, in which case I wasn't really any the wiser.

At this point I compared my specimen with my notes and photos of the venusta I had identified above, and started to suspect that whatever they were, they were the same species (I later compared the specimens side-by-side and that didn't give me any cause to doubt this, although the second one had a slightly longer and proportionately narrower rostrum). I didn't feel so worried about the variation in the elytral scales - enough of them were clearly bifurcated almost to the base that the few that weren't didn't feel like they should be a problem. This time there were absolutely no bifurcated scales along the midline of the pronotum with the exception of the thicker pale scales at the base of the pronotum. It was hard to see, but I think at least some of these were slightly notched at the tip. I don't feel that's a dealbreaker for venusta, but I still had the question of whether I can rule out meles. Duff says the pronotum on meles should be about 1.3x as wde as long - I made it 1.2x on mine. Hackston says "broader than long" for meles and at most only slightly broader than long for venusta etc. 1.2, allowing for vagueries in measuring, could be classed as "about 1.3" but it could also be classed as "only slightly broader than long", so this was of limited help so far. However, looking at photos of the two species, photos of meles consistently show a more distinctly transverse pronotum on meles, the sides being distinctly roundedly protruding in the middle. That is quite different from my specimen. Moreover, Duff gives a size range of 3.9 to 4.8mm for meles (and 3.1 to 3.8mm for venusta). Mine was about 3.35mm so comfortably within the range for venusta and too small for meles. So in the end, I think this is Hypera venusta (though as always I welcome feedback).

apparent Hypera venusta showing sides of thoracic sterna, elytral scales, elytra from side, pronotum, head from above, eyes and rostrum (from above, two views from side plus one side view including pronotum), Wendling Beck Environment Project (Norfolk, UK), 21st March 2024