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I found this tachinid on yarrow in july in north london. The dusted tergites suggests L. anthracinum which is apparently common in south europe so it's most likely, but how can I be sure it isn't one of the other 3 possible species in the key? eg crassum, tetraptera or turonicum?

It seems to have 2-3 rows of hairs on the parafacial.

Can the frons width be used to determine the species?

I cannot see a difference between the dusting on the hairy part of the cheek compared to the hairy part. There's also something about the tergites and some diagrams which I can't quite figure out unless they are dorsal views. Are close-ups of the genitalia likely to help - they're hooked out and ready - or is it just that view of the last tergites that's important?

Jeremy

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Hi Jeremy

Yes, this is Leucostoma and yes, males are very difficult to identify.
Do you have more species ??
If so, we'd really need a good look at the latter tergites in ' dorsal' view.
Do you have the key to Central Europe (Tschorsnig & Herting) ?

The difference in dusting on the head can only be found by playing with the light and shifting angles: impossible to see in a still.


Theo

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thanks Theo,

yes it's the key to Central Europe (Tschorsnig & Herting) that I refer to in my question, couplets 5-7 for this genus, and figures 193, 194, 188 etc. I'll try and get a close-up dorsal view of the terminalia then and hopefully match it to one of the illustrations. At the same time I'll try tilting the head and light-source to see what dusting becomes evident

Jeremy

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Hi Jeremy,

I did not check, but is it not the case that only one species is known for the UK ? (L. anthracinum.)


Theo

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Sorry, I meant simplex, my mistake.

Theo