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#1 2014-08-03 13:08:16

pbrighto
DF Members
Name: Phil Brighton
From: Warrington
Registered: 2011-10-21
Posts: 350

Sturmia bella?

Using the Belshaw (1993) key to identify this tachinid did not give a satisfactory result. So I browsed on the tachinid recording scheme site gallery and hey presto! it seems a dead ringer for Sturmia bella.  Since this notorious parasite of the small tortoiseshell was only first recorded in the UK in 1998, I believe, this all adds up.   I hope you can also see on the rear view shot a comb of bristles on the rear tibiae which is a feature mentioned on the website.  I would be grateful if this ID can be confirmed or if there are any subtle confusion species to check for?

Small tortoiseshells seem to have rebounded from the low a few years ago.  Does this mean S. bella has been exonerated as a major factor in their decline?   We seem to be at the Northern limit here on the Mersey.


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#2 2014-08-03 13:19:32

jeremyr
DF Members
Name: Jeremy Richardson
From: Tottenham
Registered: 2012-12-31
Posts: 222

Re: Sturmia bella?

Nemorilla floralis possibly

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#3 2014-08-03 15:32:00

pbrighto
DF Members
Name: Phil Brighton
From: Warrington
Registered: 2011-10-21
Posts: 350

Re: Sturmia bella?

This was a possibility I considered, but ruled out on eye size - it matches figure 58 in Belshaw which would lead to Carcelia etc, but neither scutellum nor palps have any orange.

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#4 2014-08-04 01:57:46

jeremyr
DF Members
Name: Jeremy Richardson
From: Tottenham
Registered: 2012-12-31
Posts: 222

Re: Sturmia bella?

yes I found couplet 59 a bit tricky by itself. The gena on your fly is at least double that of a Carcelia though, and the difference looks clear with two vouchers side by side. I'm convinced your fly is Nemorilla, but that is based only on the few I know

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#5 2014-08-04 21:50:44

pbrighto
DF Members
Name: Phil Brighton
From: Warrington
Registered: 2011-10-21
Posts: 350

Re: Sturmia bella?

The second photo is not quite side on, and in the microscope the gena looked very narrow indeed.  However, measuring it very carefully with a graticule, I get a ratio of 9 which is probably close enough for Nemorilla.   We seem to be around the Northern limit for both here, so a good find either way.

Last edited by pbrighto (2014-08-04 22:08:56)

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#6 2014-08-04 22:07:01

ChrisR
Administrator
Name: Chris Raper
From: Reading, UK
Registered: 2008-03-08
Posts: 392
Website

Re: Sturmia bella?

Yeah, the humeral callus bristles and white hairs behind the head are fairly indicative of Nemorilla floralis smile

When you see a Carcelia you really understand the gena character - it has to be incredibly thin smile   Also, as a secondary feature Carcelia/Senometopia have hairs on the posterofordal side of the hind coxa, which is a very rare feature in tachinids.

Last edited by ChrisR (2014-08-04 22:10:20)

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#7 2014-08-05 20:20:48

pbrighto
DF Members
Name: Phil Brighton
From: Warrington
Registered: 2011-10-21
Posts: 350

Re: Sturmia bella?

Thanks very much for your help, Jeremy and Chris.   Indeed having got over the eye-height problem, the other characters indicate Nemorilla according to Belshaw.

I am now wondering where Sturmia would run in the Belshaw key?  Just so I know if one turns up!

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#8 2014-08-06 14:11:09

ChrisR
Administrator
Name: Chris Raper
From: Reading, UK
Registered: 2008-03-08
Posts: 392
Website

Re: Sturmia bella?

They run out much later - arista bare, eyes bare, bare r1, bare r4+5, median vein bent with no petiole, no parafacials, no facial ridge bristles, no median discals, crossed apical scutellars, usually have orange scutellum and a bristle comb on the hind tibia. They are a really nice looking tachinid with an overall silvery grey dusting and most of the smaller bristles laying prone with a few stronger bristles on the margins of tergites 3 & 4 (I think - working from memory here!) wink

Some photos here

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#9 2014-08-07 11:42:57

pbrighto
DF Members
Name: Phil Brighton
From: Warrington
Registered: 2011-10-21
Posts: 350

Re: Sturmia bella?

Thanks, Chris.  I'll look for a specimen at the Liverpool Museum next time I'm there.

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