Diptera.info

Posted by ChrisR on 12-11-2007 19:35

Just wanted to show here some photos of some of Ivan Perry's exhibits at this year's British Entomological & Natural History Society (BENHS - http://www.benhs....) exhibition at Imperial College (London) on Saturday 10th November.

Ivan is an amazing dipterist who seems to find rarities every year and has added 3 species to the British tachinid list in the last 2 years. This year he gave me 3 more specimens, which if confirmed, might add 2 more species to the list too!

I'll start with Opesia grandis, an extremely rare species throughout Europe - found in 2006 and 2007 near Cambridge.

Edited by ChrisR on 12-11-2007 19:45

Posted by Kahis on 12-11-2007 19:52

You wouldn't have a photo showing exactly how the first three flies are mounted. A micropin through the pleurae? But what keeps the rather large - in relation to a micropin - flies from rotating and shedding bristles and legs? Just very careful handling? :o

On any case, the end result looks very good indeed.

Posted by ChrisR on 12-11-2007 20:41

I actually use side-pinning for 95% of my specimens - just like Ivan does and I haven't had any problems with flies rotating on the micropin. :) I think it really depends on a few things: the micro-pin shouldn't be too thin (I use 0.38-0.45mm diameter for most medium-large specimens) and the pin should be inserted at a slight angle - so that you don't destroy the same feature on both sides of the fly. The only difference is that I orient my specimens differently to Ivan, but the principle is the same.

I prefer this method because everything is visible (in top-down pinning it's often more difficult to see the prosternum and legs) and the specimen is protected very well from vibrations etc. :) They also take up a bit less space too ;)

Edited by ChrisR on 12-11-2007 20:45

Posted by Tony Irwin on 14-11-2007 01:23

Like Chris and Ivan, this is the system I use - if the fly is fresh, freshly thawed (from frozen) or freshly relaxed (from dry), then the muscles in the thorax will dry on the micropin and "glue" it in place. You can see that the stages are made of polythene foam; - this absorbs any vibration from handling the main pin, and grips the micropin firmly so that it doesn't rotate. I also micropin syrphids (from the top), up to the size of Eristalis and stage them on foam. They seem to suffer less damage than they used to when I did direct pinning.
(I still use direct pinning for bigger syrphids and tabanids.)

Posted by Kahis on 14-11-2007 15:32

Chris Raper wrote:
I think it really depends on a few things: the micro-pin shouldn't be too thin (I use 0.38-0.45mm diameter for most medium-large specimens) and the pin should be inserted at a slight angle - so that you don't destroy the same feature on both sides of the fly.

Thanks for the description. But where did you find such large micropins? The largest I have seen for sale is 0.20 mm.

Posted by ChrisR on 14-11-2007 20:12

I use Watkins & Doncaster (www.watdon.com) D3 micro pins for most tachinids and A1 for the smaller stuff, like Siphona or Actia - though I have considered trying the Czech entosphinx pins. The main 'stage pin' is a 38mm continental pin at about >=0.5mm. The stage pins can be as thick as you like but the thicker the better so that they are easy to hold and don't flex when being pushed into cork etc. :)

Posted by ChrisR on 15-11-2007 00:43

#11

Well spotted Theo ... a combination of a typo and there seems to be some confusion in the UK literature regarding the correct specific name. The current name should be Zenillia libatrix (Panzer, 1798) according to Belshaw & FaunaEuropaea but Chandler cites:

ZENILLIA Robineau-Desvoidy, 1830
fulva (Fall?n, 1820 ? Tachina)
=libatrix (Panzer, [1798] ? Musca), preocc.
=macrops (Brauer & von Bergenstamm, 1891 ? Myxexorista)
=ciligera: authors, misident.
=fauna: authors, misident.

which is probably where Ivan's and my confusion has occured. In my current draft of the new British tachinid handbook libatrix is used :)

Posted by ChrisR on 15-11-2007 11:59

#12

As a follow-up, for anyone with a copy of Chandler here is Peter Tschorsnig's explanation (pers.comm) of why libatrix is the correct name, over fulva:

Well, this is the unlucky case of the old names described in the genus Musca (in the sense of the old authors, i. e. belonging to many diverse families and genera today).

When Panzer in 1798 described his tachinid Musca libatrix, there was already a Musca libatrix existent, named by Scopoli in 1763, but this Musca libatrix of Scopoli is a Syrphidae (according to the Catalogue of Palaearctic Diptera its valid name is Sphaerophoria scripta Linnaeus, 1758). So Musca libatrix of Panzer is a primary homonym of Musca libatrix Scopoli, and when strictly applying to Art. 57.2 Panzer's junior name would be invalid. This was the reason why Chandler changed the name to fulva Fall?n, a mere formalism and not helpful in my opinion. It is clear, however, that Zenillia libatrix fulfills the condition of Art. 57.2.1 (which refers to Art. 23.9). So Zenillia libatrix remains valid because it is a nomen protectum (you may find the full text of the ICZN articles on http://www.iczn.o.../index.jsp).

There was never a problem with the use of the two names. Nobody ever confounded libatrix Scopoli and libatrix Panzer because the species are of course quite different and systematically widely separated, and even the names could not have been confounded because libatrix Scopoli was not used as a valid syrphid name. Art. 23.9 was introduced to the Code to avoid such unnecessary changes of names.

Chris R.

Edited by ChrisR on 15-11-2007 12:03

Posted by ChrisR on 15-11-2007 18:08

#14

Opesia grandis is incredibly rare *everywhere* ;) I received this from Peter Tschorsnig:

Opesia grandis is widespread in Europe (but - as far as known up to the present - obviously not in the typical hot Mediterranean or cold Northern countries). There are only scattered records everywhere so it must be regarded as a rare or very rare species (I never collected it by myself, Herting collected only a single specimen).

Eurthia intermedia in Tschorsnig & Herting (1994):

Europe to Scandinavia ... Dry, warm areas. End April to Mid June, 1 generation. On Euphorbia-flowers; rare. Host unknown.

Zenillia libatrix in the same publication:

Europe to Scandinavia; NS, NW, BW, BY, NB / A, CH. Bushes, forest edges. End April to Mid September (especially May), probably 2 generations. In open areas slightly commoner than the previous species [Zenillia dolosa], and also most often reared from the host.

So, they're all quite rare and all but Opesia grandis might be commoner in the south :)