Smallish dark hoverfly ID

[Lord V]

Spotted this small dark hoverfly feeding on a potentilla flower yesterday About 8mm body length
Any ideas on ID ?
Thanks
brian v.

[EDIT] Ah - guessing it might be Cheilosia caerulescens

[Geoff F]

Black hoverflies I'm afraid, Brian, are a real nightmare to identify. However those are clear photos with good detail.

So, assuming it is a Cheilosia (I have jumped a few early ID Key stages here) we have a non hairy face and orange front tarsus. Which seems to put it at C. albitarsis. Or C. ranunculi which is virtually identical.

C. mutabilis is a rather small alternative and there are a few other points which seem doubtful in this case.

But, like I said, this is a difficult family so another opinion is always welcome.

ps. Where did you find C. caerulescens? I can't find any reference to this species. Possibly a European species?

[Lord V]

Originally Posted by Geoff F

Black hoverflies I'm afraid, Brian, are a real nightmare to identify. However those are clear photos with good detail.

So, assuming it is a Cheilosia (I have jumped a few early ID Key stages here) we have a non hairy face and orange front tarsus. Which seems to put it at C. albitarsis. Or C. ranunculi which is virtually identical.

C. mutabilis is a rather small alternative and there are a few other points which seem doubtful in this case.

But, like I said, this is a difficult family so another opinion is always welcome.

ps. Where did you find C. caerulescens? I can't find any reference to this species. Possibly a European species?

Thanks for the help Geoff.
The C.caerulescens came from here Diptera.info - Photo Albums: Syrphidae
Yes it is a European site but thought it looked remarkably similar to my pics.

Brian v.

[Anomalous]

Originally Posted by Geoff F

we have a non hairy face and orange front tarsus. Which seems to put it at C. albitarsis. Or C. ranunculi which is virtually identical.

Not sure what this hoverfly is, but it is definitely not C. albitarsis/ranunculi, as that pair have all black legs, with just a small orange patch on the front tarsi. This individual has extensively orange tibiae, with a dark ring.

Ian

[Geoff F]

The key says 'mainly black' and that is a rather dusky orange.

But one other item which did rather worry me is the length of the scuttellum marginal hairs.

If we, as an alternative, go down the Pagana Group line it possibly comes out at C. scutellata. But that has a yellow rear edge to the scuttellum. Looking carefully at one of the photos there does appear to be some very faint paler colouration. So this may be another thought.

But working from those photos this does mean taking a couple of 'leaps in the dark' with the ID keys.

Perhaps somebody with more experience in this group can instantly recognise something here.

[Lord V]

Thanks Ian and Geoff for the further ideas.
BTW I gather C. caerulescens is in the UK just not in the books yet.
Brian v.

[Geoff F]

That is something for Roger to consider then Hoverfly Recording Scheme - Home

This thread did prompt me to look again at one of my similar unidentified hoverflies. Similar but not identical to yours. However, after spending about 15 minutes for no advance in ID, it has been returned to the questionable files until I have more time.