Help with two mining bees, please

[Dillybythesea]

Am having serious senior moments with my bees today and would love somebody to put me out of my misery! I'm sure I should know what this is, but am confused by the pale hairs on the hind femur and tibia of this Andrena female, which was big, say 14mm.



Second confusion - is this (which was say 8mm), a Lasioglossum sp? I'm trying to deduce identifying characteristics from pictures online - which you're probably going to say is a silly game, but how else?!

[JRsbugs]

First is Andrena carantonica.

Second probably Lasioglossum calceatum. I use pictures online too! I try to make sure the source is reliable though.

Janet

[Jason Green]

Evening Dill,

The first looks like Andrena carantonica, sort of 'fat and shiny'! The second looks great for Lasioglossum, good work. I wonder if the orange banding along the posterior margin of each tergite is important here?.

Take care,

Jason

[Dillybythesea]

Thank you so much Janet and Jason! It's SO nice to put a name against and move on!

And yes, wouldn't it be nice to know for sure if 'the orange banding along the posterior margin of each tergite is important here'?

[Matt Smith]

Originally Posted by Dillybythesea

Am having serious senior moments with my bees today and would love somebody to put me out of my misery! I'm sure I should know what this is, but am confused by the pale hairs on the hind femur and tibia of this Andrena female, which was big, say 14mm.



Second confusion - is this (which was say 8mm), a Lasioglossum sp? I'm trying to deduce identifying characteristics from pictures online - which you're probably going to say is a silly game, but how else?!

I would not worry too much about the ventral side of the tibia, this is not where you need to look, the hair colour characters for the hind tibia refer to the dorsal margin of the hind tibia.

The second bee is a Lasioglossum. With this group, most of the key characters such as the carina (ridge) along the side margin of the propodeum (the back face of the thorax) or the sculpture on the surface of the top of the thorax or the tergites are small or well hidden and rarely show show up in "whole insect" photos.

To separate female L.calceatum from L.albipes you need to consider the following characters:

Density of punctures anterior to median ocellus closer, more crowded and smaller than those at mid-point between a lateral ocellus and antennal socket. In full face view, head broadly rounded, not subelongate. Outer, longitudinal carinulae of metapostnotum extending obliquely across lateral
shoulders of propodeum. In profile, disc of gastral tergite 2 with sparser, short, semi-erect and decumbent hairs. Length 8-10 mm. calceatum (Scopoli).

- Density of punctures anterior to median ocellus not differing significantly from those at mid point between a lateral ocellus and antennal socket. In full face view, head less broad, more elongate. Outer, longitudinal costulae of metapostnotum not extending obliquely across lateral shoulders of propodeum, the surface at this point without rugosity. In profile, disc of gastral tergite 2 with more abundant, short, semi-erect and decumbent hairs. Length 7-9 mm. albipes (Fabricius).

The orange colour of the marginal area of the tergites is of little use as a diagnostic character in this case

[Dillybythesea]

[quote=Matt Smith;752809]I would not worry too much about the ventral side of the tibia, this is not where you need to look, the hair colour characters for the hind tibia refer to the dorsal margin of the hind tibia.

Many thanks indeed Matt! A tip like that is such a boon. I've been trying to use the female Andrena test key on BWARS and never get past the first hurdle, but perhaps now I will!

And many thanks also for the detailed info on Lasioglossum. It definitely helps to know how subtle are the distinctions - if only to know when one's beat!

Added to which you've defined several terms, and raised others, all of which I can now sort through, add to my diagram and try to absorb.

Much appreciated! Rhona