Megachile ID

[runnerwill]

Hi, I'm still struggling with bees. This leafcutter female was at RSPB Fen Drayton on sunday. It was a large bee, so maybe willughbiella, but I don't have the key available so not sure. Help appreciated!






Cheers

Will

[JRsbugs]

I'd say Megachile versicolor.. check the photo on flickr, this person seems to know his bees. T6 looks to have adpressed hairs only, and is less broad with a slight indentation in the middle. It's also feeding on the same flower!

[Jason Green]

I'd say you're correct with willughbiella. You can quite clearly see semi-erect black hairs on the sixth tergite which rules out versicolor, as does only the pale sternal pilosity of 2-4.

[runnerwill]

Thanks both, I managed to get hold of the key today and willughbiella does look like the better bet.

[JRsbugs]

Originally Posted by runnerwill

Thanks both, I managed to get hold of the key today and willughbiella does look like the better bet.

Can you tell me the reasons for this choice?

[Jason Green]

I've just had my specimens of willughbiella and ligniseca out under the microscope and believe there's a case for this being the slightly less-common latter.

I'd much prefer to check it out microscopially to confirm the coverage of hairs on T6, but with that not being possible then I suppose Megachile willughbiella/ligniseca will do for a photograph

[runnerwill]

Hi again, I've had an expert take a look at the photos on flickr, and for a number of reasons (adpressed hair on tergite 6, thin terminal bands on tergites 2-5, steep angle between tergites 5 and 6 and the scopal pattern merging smoothly from pale through to orange and then dark posteriorly) he's identified my bee as ligniseca.

[JRsbugs]

Originally Posted by runnerwill

Hi again, I've had an expert take a look at the photos on flickr, and for a number of reasons (adpressed hair on tergite 6, thin terminal bands on tergites 2-5, steep angle between tergites 5 and 6 and the scopal pattern merging smoothly from pale through to orange and then dark posteriorly) he's identified my bee as ligniseca.

That would make more sense, ligniseca is the alternative in the final couplet with versicolor. T6 certainly does look to have adpressed hairs, not erect and numerous as in M. willughbiella. The final determination was a little tricky, I was pondering over the black hairs on the scopa and the colour of the orange hairs, that can be tricky depending on light, pollen and age. The final sternites did appear to have some black, and as there is an Irish form with all yellow again tricky. The shape of T6 was another tricky one, but with experience I guess it gets easier.

[JRsbugs]

I have found a photo of M. cf. ligniseca showing the tip of T6, the keys state it is broadly rounded with no indentation which this shows..

Megachile cf. ligniseca f #1 | Flickr - Photo Sharing!

The final decision I made of it being versicolor was the apparent slight indentation at mid-point which versicolor can sometimes have.. this photo seems to show a slight indentation..

[Matt Smith]

Originally Posted by JRsbugs

I have found a photo of M. cf. ligniseca showing the tip of T6, the keys state it is broadly rounded with no indentation which this shows..

Megachile cf. ligniseca f #1 | Flickr - Photo Sharing!

The final decision I made of it being versicolor was the apparent slight indentation at mid-point which versicolor can sometimes have.. this photo seems to show a slight indentation..

If the "indentation" is the bit I think you are looking at, this is an artefact caused by Tergite 6 (T6) overlapping and extending slightly further back than Sternite 6 (S6), giving the impression of a slightly "Y" shaped indentation. The rear of T6 is above and to the left of this point and I can't see any sign of a dent in the tip.