Dung Fly - possibly Suillia sp. for identification

[Bruce Williams]

Stony Stratford, Bucks.

I'm basing Suillia on a very similar looking fly I posted back in June 2008, see: Pinkish dung fly for id

I'm hoping for confirmation of id (maybe even species?) before I post to the Gallery.



Bruce

[ladyhawk]

Thanks bruce you have just put me in the right direction for a fly that i have been trying to id, but not yours sorry thanks again. my fly is Suillia simillis one that looked like yours is umbractia but am still learning

[oxycera]

Suillia is distinguished amongst Heleomyzids by the presence of a single orbital bristle.
S.umbratica and S.similis are not British.
Your specimen is probably S.affinis.

[ladyhawk]

Thanks will have a look again later at my pic, when i finish work

[oxycera]

Originally Posted by ladyhawk

Thanks will have a look again later at my pic, when i finish work

Just to avoid any confusion, I was referring to Bruce's pic.
These are quite difficult to identify from photos unless you have a key as well; and images as good as Bruce's (and even then I think you must err on the side of caution).

[JRsbugs]

Originally Posted by oxycera

Just to avoid any confusion, I was referring to Bruce's pic.
These are quite difficult to identify from photos unless you have a key as well; and images as good as Bruce's (and even then I think you must err on the side of caution).

On that point I would err on the side of caution, as said these are very difficult and require expert knowledge. Andrzej Woznica is the Helomyzidae expert on diptera.info, he will often not give an ID to species unless he can see the details he needs to see however good the photo is.

We have a few Suillia sp., check out all those bristles you can see under the femora, which Suillia laevifrons also has. Note in particular the hind femur.


I don't see that many bristles on Suillia affinis.

Janet

[Laurence Clemons]

I agree with John - Suillia affinis.

[JRsbugs]

Originally Posted by Laurence Clemons

I agree with John - Suillia affinis.

Laurence, I appreciate your knowledge of diptera and I know you have a lot of experience in this field.

Please tell me why then this is Suillia affinis, I can't see the bristles on the hind femora match that at all.

Look at this pic on diptera.info of S. affinis, you can enlarge the pic to get an even better view. There are bristles on the ventral side of the hind femur visible, but they don't look as dense and long as those on Bruce's fly. I realise pics are not always the best to go on, but the bristles on the dorsal side of the hind femur don't match either.

I am not saying it is Suillia laevifrons, I have not enough experience to say that for sure but it sure doesn't look like S. affinis to me. In the interests of knowledge and the absence of having any keys I appreciate any pointers which would help to identify any of these.

[Jason Green]

Evening Bruce,

I haven't any experience with chaetotaxy, so am just interpreting what I see here. Going with John's point - he says affinis has one orbital bristle. The one Janet posted from Diptera.info it lacks the bristle - and so I assume this rules out Bruce's fly being laevifrons, and the unique point with affinis is present (uniue among Heleos, a confirmatory character) - meaning it's affinis.

What key did you use John, and Janet? It's worth remembering that keys are more accurate with regards to identifications - comparing images is a good method with quite a few, but with these flies (I should probably include all the other tougher groups - tachs, Calliphs, etc.) will have more subtle differenes - even just a single hair, as is the case here. I don't think it would need comparisons with every hair on the insect, just a look for the ones the key suggests.

Apologies if I've made a mistake anywhere there - I'm in the middle of 12 to 15hr-long shifts at work at the moment and should probably avoid WAB-use during this period!

Take care,

Jason

[JRsbugs]

Originally Posted by Jason Green

Evening Bruce,

I think Heleomyzids like this are best done with keys, or have personal experience in having keyed some out - for kind of 'intuition'. I lack this, and haven't any experience with chaetotaxy, so am just interpreting what I see here.

Going with John's point - he says affinis has one orbital bristle. The one Janet posted from Diptera.info it lacks the bristle - and so I assume this rules out Bruce's fly being laevifrons, and the unique point with affinis is present (uniue among Heleos, a confirmatory character) - meaning it's affinis.

What key did you use John, and Janet?

Apologies if I've made a mistake anywhere there - I'm in the middle of 12 to 15hr-long () shifts at work at the moment and should probably avoid WAB-use during this period!

Take care,

Jason

Yes Jason, I think unless you do know what you are looking at it would have been better staying away regardless of whether or not you are doing long shifts.

I didn't use any keys, I don't have any, but I do take careful notice of identified flies in the galleries at diptera.info. Generally, if the bristles are all checked and are all present and all else fits it usually is a good sign that you have correctly identified the fly, but confirmation is always a good thing unless you happen to know there is no other similar fly hiding a spare bristle somewhere.

I have just had a fly confirmed as Suillia affinis, if you would like to see what one really looks like. Take careful note of the bristles on the hind femur, and all those bristles hanging off the ventral area between the 1st and 2nd legs of Bruce's fly which are not present in S. affinis.