Female cuckoo bee

[peterbolson]

From my garden yesterday.
I've had a close look and T6 is shiny without a keel. The callosities on the ventral surface of the 6th plate are V shaped & end near the tip. So I think it is probably P.bohemicus, which I've not seen before, but I would welcome an expert opinion.
Thanks
Peter

[peterbolson]

I've had another & better look at the genitalia & now think that the ventral ridges are inconspicuous ( I don't think I was looking at the right part before - these cuckoo bees are new to me ). Also the tail is difficult to see because it is turned under. And there is no yellow at the sides of T3. Length by the way about 15mm.
So I now think it's Psithyrus ( or should it be Bombus ? ) sylvestris.
An expert view would still be much appreciated.
Peter