Andrena clarkella??

NickU · #1 (**permalink**) 09-05-2010, 08:01 PM

I know Andrena spp.. can be tricky, but can anyone confirm this is most likely to be a female Andrena clarkella?

C 12mm Wiltshire garden, 15.4.10

Nick Upton - naturalist/photographer

NickU · #2 (**permalink**) 09-05-2010, 08:03 PM

Here's the pic:

runnerwill · #3 (**permalink**) 12-05-2010, 03:58 PM

That's a male Andrena, afraid I wouldn't want to hazard a guess as to which one.

eucera · #4 (**permalink**) 12-05-2010, 04:09 PM

Certainly a male Andrena, and although these can be mighty tricksy, I suspect this is a male A. fulva

NickU · #5 (**permalink**) 12-05-2010, 09:07 PM

Many thanks for the feedback. I'd be grateful to know how one can be sure of the sex of Andrena spp.

I took this to be the female of Andrena fulva:

and, naively, maybe, thought this was the male A. fulva

and thought the first image I posted was of another species with far fewer hairs on the abdomen, maybe A. clarkella or A.hearmorrhoa, but these are notoriously hard to be sure of I gather.

eucera · #6 (**permalink**) 13-05-2010, 08:22 AM

Hi Nick

Both of the 2nd batch of pics you have posted are female Andrenas. The first, as you surmise, is A. fulva. There is absolutely nothing like it in northern Europe at all.

The second pic is less obvious, and I am not certain what species it actually is.

Female Andrena (in common with many other genera) have pollen collecting apparatus called a scopa. In Andrena, this is in the form of modified hairs on the hind leg. Females tend to be more boldly marked, and generally bulkier. They live longer and have a load of eggs on board so the greater size is not surprising. Also, the female antenna has 12 segments and the male has 13.

NickU · #7 (**permalink**) 13-05-2010, 10:24 AM

OK, many thanks for the good advice. Am starting to tune in more now. So I have a definite female A. fulva (there have been lots about in my garden this year), a query male A.fulva (first image), though they usually look hairer on the abdomen in photos, but the front on angle may be deceptive. I have no close ups of the mandibles to see if they have the downward projecting tooth at the base. The third image is a Andrena sp. as so many look like this, but I'd like to add a 4th image, which I think must be a female, looking initially very like the first image, but with hairier legs and I'm thinking maybe it's Andrena thoracica- with very shiny black abdomen and very dark hairs on the legs. No doubt it will be consigned to the Andrena sp. category, though, without microscopic intervention! If this IS a female A. thoracica, I can find no images of male A.thoracica to know if my first image might be this rather than A.fulva. Andrenidae... tricky..

eucera · #8 (**permalink**) 13-05-2010, 02:21 PM

This one is A. nitida female. Thgere is a patch of pale hair at the front of the abdomen at the sides. This is diagnostic.

The long pale hairs on the front of the face of the male Andrena would rule out thoracica, which has only black hairs.

A. thoracica is almost entirely coastal now in distribution.

NickU · #9 (**permalink**) 13-05-2010, 08:33 PM

Many thanks for the great feedback. This all just shows how tough many Andrena sp. are to be sure of unless you know EXACTLY what to look for and can see the relevant bits! I'm confident with (female) A.fulva and A.cineraria now, would know A.nitida again, and am struggling with the rest! I saw another male like pic 1 again today and it did look hairier on the abdomen when it turned in the sun, so maybe A. fulva males are the orange thorax, black abdomen individuals I'm seeing (or some of them!).