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#1 2017-11-07 14:26:14

Gateside
DF Members
Name: Nigel Gilligan
From: Cumbria
Registered: 2011-08-26
Posts: 906

Tipulidae with abnormal venation - give up?

Sorting out time...  I have this large, strange cranefly (dating from May), that for some unknown reason I'd postulated could be a male Tipula vernalis.

Having compared with the Tipulidae wings on the kolumbus web site, none of the ones shown have the strange feature of apparently having 2 discal cells. The left and right sides are compared, and they both have the extra discal cell, but there are clear differences anyway which cannot be explained by the slight difference in tilt.

My thoughts are to simply give up on this one. I can't see any other body feature which stands out, so it doesn't seem possible to ID without the actual specimen. Anyone else have an opinion?

Nigel G.


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#2 2017-11-07 19:28:50

AliCullaloe
DF Members
Name: Array Array
Registered: 2014-08-20
Posts: 56

Re: Tipulidae with abnormal venation - give up?

I'd guess a brown costa with pale stripe below, grey thorax/abd with thin dark stripe looks like T.oleracea?  Genitals also look ok for a male of that species. Can't see what size it is really though. Happy to be corrected!

Cheers
Ali

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#3 2017-11-07 20:57:58

Gateside
DF Members
Name: Nigel Gilligan
From: Cumbria
Registered: 2011-08-26
Posts: 906

Re: Tipulidae with abnormal venation - give up?

Thanks for those comments, Ali.
It could well be T. oleracea, but I wouldn't like to go any further than that.
I am unhappy about the dark smudge across the thorax mid-way. It isn't a shadow, so that is an oddity.

I think I won't be logging this one, unless somebody can come up with an explanation about the anomalies!

Nigel

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#4 2017-11-14 18:23:58

johnkramer
DF Members
Name: John Kramer
From: Oadby, Leicester
Registered: 2008-02-20
Posts: 230

Re: Tipulidae with abnormal venation - give up?

It is T. oleracea.  There are a number of possible explanations for the aberrant venation.  One would be somatic mutations, anther would be some environmental factor(s) causing a change in the normal development.  [Since the variations are not symmetrical I think that these are unlikely to be a genetic mutations.]  As far as I know, there are no papers on this topic.  Some species seem more prone than others so it could also be due to the occurrence of rare double recessive alleles.
John K

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#5 2017-11-14 18:50:46

Gateside
DF Members
Name: Nigel Gilligan
From: Cumbria
Registered: 2011-08-26
Posts: 906

Re: Tipulidae with abnormal venation - give up?

Thanks very much for the ID, John.
I haven't kept a log of abnormal craneflies in this location, but it isn't my first one I'm sure.
But I guess there is nothing I can do about it.

Nigel G.

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