Blackbird's picture

Tiny golden bee with green eyes

Observed: 22nd May 2012 By: BlackbirdBlackbird’s reputation in Invertebrates
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Description:

Possibly a male, behaved like it was patrolling. It was around for a while, but never managed to get very close photos, too nervous and warm to stay put.

Identifications
Species interactions

No interactions present.

Comments

ianbeavis's picture

Osmia coerulescens or leaiana

This could also be O leaiana. Males are very similar, though females are quite different. There are good diagnostic features (especially declivity at base of abdomen, smooth & shining in coerulescens but matte textured in leaiana) but can't be seen in photos. In my experience, leaiana is generally larger but this only helps if you're already familiar with both.

Blackbird's picture

Osmia caerulescens or leiana

Is eye colour diagnostic? All identified leaiana photos i've seen show dark eyes. Hair colour and the bronze shininess also appear different. eucera (Stuart Roberts) at WAB mentions a notch at the end of abdomen in leaiana. I managed a back shot at abdomen (no notch visible) and might see the declivity shininess too in another shot.

ianbeavis's picture

Distinguishing O coerulescens & leaiana

Eye colour isn't mentioned as diagnostic in any literature I have. Of course, this fades in death anyway so can't be checked in preserved specimens. Again,the literature agrees that hair colour and metallic sheen are the same in both species. I can't see any such superficial difference in my specimens, other than leaiana being consistently larger. Both have some sort of notch in the last abdominal segment: it's just differently shaped. Because it's tucked underneath, I'm not convinced it would show up in a photo, or that you could see into the gap between abdomen and thorax. I think we have to admit limitations of photo ID here and I would encourage people to net a specimen. You don't have to kill it if you find that problematic: examination in the hand with a lens should do the job.

jeremyr's picture

A notch? I could probably

A notch?
I could probably catch one of mine tomorrow, do I turn the bee over and scrutinise the end of the abdomen? I don't have a hand lens yet so I'll try it with the macro/18mp-crop technique. It's worked (just) for sutres on the head of a cryptops which was smaller so I'll give it a go. If that doesn't work I'll get a hand lens.

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ianbeavis's picture

Best distinguishing features

I think the 'declivity' of the basal abdominal segment (where it drops down to meet the thorax) is the best character - brightly shining in coerulescens, matt in leaiana.
The problem with the 'notch' is it's a 'picture's worth a 1000 words' situation! George Else's draft key distinguishes as follows:
Coerulescens: Posterior margin of gastral tergite 6 on each side of median notch unevenly crenulate; notch narrow, shallow & often forming part of crenulation.
Leaiana: Posterior margin of gastral tergite 6 on each side of median notch, even; notch broad and semicircular.