Beetle for identification - family?

[MattPrince]

Hello,

Found two beetles of similar form whilst grubbing in leaf litter for spiders (in a beech forest in Wiltshire). Initially I thought they were carabids, one of the types with truncate elytra, as I could see they had lobed trochanters, filiform antennae... but the number of abdominal segments under the body seems wrong - I make it 5 including the segment bearing the hind legs..

So.. is my counting at fault? Am I barking up the wrong tree?

Any pointers to correct family, and where I'm going wrong would be gratefully received.

Regards,
Matt

[Jason Green]

Yes, Carabidae sub-family Lebiinae and possibly species Paradromius linearis.

Do you still have the address of my website-in-testing? It's the fourth Libiine carabid, and includes a ventral photograph of it - you may be able to compare it to your specimen. I think that pop-up opens to a rather reduced size so will need 'maximising' your end.

Hope this helps.

[MattPrince]

Thanks Jason - the underside is identical. What threw me is that I make it 5 ventral segments including Coxae, and that seemed to conflict with the expected 6 (for most carabids).

It does indeed look very close (in fact there is another smaller specimen which looks very close to d. atricapillus also on your site, just visible in one of my photos).

Another thing that made me wonder is that p. linearis habitat definition in Luff seemed to suggest a riverine link - whereas the specimens were taken in beech/oak woodland a fair way from the nearest pond.

I'll revisit the specimens and post my findings.

Thanks!

Matt

[Jason Green]

Originally Posted by MattPrince

Another thing that made me wonder is that p. linearis habitat definition in Luff seemed to suggest a riverine link - whereas the specimens were taken in beech/oak woodland a fair way from the nearest pond.

I've just checked my specimen's data-label - beaten from Oak growing in a hedgerow on a brownfield habitat. No pond within 100m or so as I recall. For a contrast-of-information I'll have a look at Lindroff later.

[Klaas Reißmann]

The bigger one is Dromius (Paradromius) linearis. The smaller one surely not. I would need more views so I can possibly tell, what the smaller one is.

Regards
Klaas

[MattPrince]

Thanks for that Klaas - here's another picture of the smaller animal with the darker head. Looks like the example of demetrias atricapillus ( from Jasons site - at least it as much as it fits with its latin name



Fraid its out of focus - however I've still got the specimens - just haven't had a chance to look at them again - so I can post more details (or even try and key them myself with Luff).

Can you shed any more light on my 'no of segments' confusion - are some of the ventral abdominal segments fused in these animals? (or appear fused) ?

Cheers for the help anyway!

Matt

[Jason Green]

Ah yes, that does look close.

Well, when you get it under the microscope check the 4th tarsal segments - are they deeply-bilobed on all legs? If so you're in the right genus. For atricapillus, the dorsal area of the head behind the eyes should have a covering of fine upstanding pubescence.

[Klaas Reißmann]

I would need a view from above. I can't tell anything by this view.

Edit: no, it is not Demetrias. By far to small. The Demetrias-species are as big or bigger than Paradromius linearis (except Demetrias imperialis - which does have very typicall black markings on the forewings). Demetrias atricapillus and Demetrias monostigma also have some black sutural markings on the forewings. I guess it will be more genus Philorhizus and in this I guess Philorhizus melanocephalus. But I'm everything but sure with this.

Regards
Klaas

[MattPrince]

LoL from one black head to the next

Thanks for the help guys - I'll check the specimen again when I get back in on Thursday (I've even added it to my ever increasing task list on the 'fone, so hopefully it will get done this time) and hopefully post a dorsal shot (and one thats in focus this time!).

Matt

[MattPrince]

Well its not much better a photo, but I think Klaas's suggestion of p.melanocephalus is a good one. The tarsal segments were not bilobed and the only dark on the elytra is a small spot at the anterior end and along the inner edge.