Thread subject: Diptera.info :: Pales pavida [Tachinidae]

Posted by Susan R Walter on 28-01-2007 22:46
#1

Is this Pales pavida? 9mm, from 21 November 2006, east London cemetery park.

Posted by Susan R Walter on 28-01-2007 22:51
#2

Dark with bluish tinge (had to check it wasn't a Calliphorid), very hairy eyes, orange tip to scutellum, arista bare, pale hairs at the back of the head, a row of neat little bristles up the face to about half way, very slight orange tinge to hind tibia.

Posted by ChrisR on 29-01-2007 01:24
#3

I haven't tried keying it (yet) but it sounds very like Pales from your description. :) That gun-metal blue colour, orange hind tibia and the strong bristles up the facial ridge are quite distinctive.

Posted by Zeegers on 29-01-2007 10:09
#4

Good call, Susan

Theo

Posted by Susan R Walter on 29-01-2007 14:15
#5

Many thanks Chris and Theo (aka Team Tachinid:D). I ran it through the key and managed to get Phorocera grandis, which, of course, is incredibly rare and anyway, once I had looked a picture, was clearly wrong. I was fairly happy that I had an Exoristinae at any rate and looked at some more pics and lo - Crex has put a couple of nice images of P palida in the gallery which made me go aha! (Sorry Chris, but better than the pic on your website;)) Then I read the description for P palida and made sure my specimen had the crucial bits - which it seems to. The very neat short little curved black bristles up the front of the white face are quite striking - they put me in mind of tribal jewellry made of boars tusks or sharks teeth. The orange on the hind tibia is so faint I would have disregarded it if not for being steered toward it with the description.

Posted by ChrisR on 29-01-2007 18:23
#6

Where do you think you initially went wrong in the key Susan? The palp colour should be fairly obvious but measuring bristle lengths can be tricky without a graticule ... and judging whether the mouth protrudes or not depends on having seen one that does ...then you'll always know one that doesn't!! :D

As you may know, I'm in the process of revising Belshaw's key and so if you have any comments on difficult couplets or the bits you like/dislike then I'd really like to hear them.

Edited by ChrisR on 29-01-2007 18:25

Posted by Zeegers on 29-01-2007 22:07
#7

Hi Sarah

Studying Tachinidae is full of dirty tricks, also known as rule of thumbs.

Let me share this one:

How to separate Exoristini from Goniini

If the Tachinid is elongated, like Sarcophaga sl, it is likely to be Exoristini or Blondeliini.

If it is distinctly plumpier than Sarcophaga, it is Goniini / Eryciini

this dirty trick would have saved you in this case


Good luck


Theo Zeegers

Posted by Susan R Walter on 29-01-2007 22:49
#8

Thanks guys.

Chris - I'll send you a pm about keys.