[ID, pinned] Nomad and Lasioglossum sp.

[Jason Green]

Afternoon all,

I have these two for ID, please. Any other angles - just ask

28/04/2010


Which Lasioglossum?
Lateral, anterior, abdomen, mandibles from below posterior which has a distinctly-curved upper tooth, and wing

This was found investigating an earthy bank with quite a shaky, shuddery flight. Next up...

28/04/2010

Is this Nomada striata (too yellow on tergite 1)?
Dorsal, lateral and anterior. Mandible is black/red and double-toothed

Found on a Dandelion near an arboreal setting.

Thanks for looking!

Take care,

Jason

[Jason Green]

Sorry, sizes! Lasioglossum - 5mm, Nomad - 8.5mm.

Now, the Nomad. I've tryed keying it out with BWARS test key - I hope this is a male! - and fully expect it to be Nomada striata. However, this is what I actually got:

1: 'Labrum black (it's very hairy, but I lifted some under the 'scope and it was still black beneath) - points to Group A.

2.1: 'Hind femur, at base beneath, with a conspicuous patch of adpressed hairs'

2.2: 'Large species with colourful markings, including pale side spots. Labrum with a large triangular projection on the median apical margin. [very rare] = N. armata

...my image of this point:

...which points to Nomada armata. As I say, I fully expect striata - so if I've keyed it incorrectly please let me know!

[Matt Smith]

1) Lasioglossum sp. Most likely to be L.calceatum / L.albipes but really needs to go under the scope at high magnification to look at the punctures on the head around the ocelli and the back edge of the propodeum to separate.

2) This is a female (count 12 antennal segments) Nomada fabriciana. Check the mandibles, they are forked at the end, only two UK species of Nomada have bidentate mandibles and only one has a black labrum.

Note - "adapressed hairs" are hairs that cling tightly / follow the contours of the body part they arise from - eg the white hairbands on the abdomen of a Colletes sp. The hairs in the picture are definately not adapressed.

[Jason Green]

Thanks Matt. So I assume the key would have worked had it been male!

So how exactly are Nomads sexed? Yes, the mandibles are indeed forked.

One last question - what book/key covers Lasioglossum? My microscope is 20x, but I'm hoping to get x40 soon. I assume that would be sufficient? I'll see if I can get a better image of the ocelli tomorrow. I'm so glad I have the chance of a re-take!

[Matt Smith]

Originally Posted by Jason Green

Thanks Matt. So I assume the key would have worked had it been male!

That I could not say. I've only briefly looked at the test key to male Nomada and it is not a key I use.

Originally Posted by Jason Green

So how exactly are Nomads sexed? Yes, the mandibles are indeed forked.

Most aculeates can be sexed by counting the number of antennal segments and abdominal segments. 12 antennal segments and 6 abdominal segments = female, 13 antennal segments and 7 abdominal segements = male. For a few genera like Ectemnius the antennal count does not work, but the number of abdominal segments does. Also, check for a sting or the presence of male genetalia.

Originally Posted by Jason Green

One last question - what book/key covers Lasioglossum? My microscope is 20x, but I'm hoping to get x40 soon. I assume that would be sufficient? I'll see if I can get a better image of the ocelli tomorrow. I'm so glad I have the chance of a re-take!

At present, there is no modern book that covers all of the UK bees to species. One has been in prep for some while, I use the test keys from this for all my bee ID's. 40X will do for most ID work, but sometimes a slightly higher magnification is needed.

[eucera]

Could you give some idea of the size of the Lasioglossum, and the colour of the thorax?

I have a feeling that this is not L. calceatum or L. albipes, but it may just be L. morio!

[Jason Green]

Evening Stuart, good to see you back!

The Lasioglossum is 5mm long, and I have a better shot showing the thorax:

If you need another shot I'll get it tomorrow (unless I have one already ). when it was 'In the field' it just looked like a typical non-descript black one, even in the specimen jar! I only realised it was most likely a Lasioglossum when I got it under the 'scope.

[eucera]

I don't know about you, but I reckon there are some metallic blue-green reflections on the top of the head and thorax.

This would be most likely to be L. morio or L. smeathmanellum (assuming it is one of the Dialictus group of Lasioglossums (we have 4 spp. in UK)

[Matt Smith]

Certainly some definate green reflections in that last shot - if it is 5mm long then Stuart is on the right track.

[Jason Green]

Originally Posted by eucera

This would be most likely to be L. morio or L. smeathmanellum (assuming it is one of the Dialictus group of Lasioglossums (we have 4 spp. in UK)

Thanks Stuart. Would it be feasible to get further? I have a 20x microscope.