Posted by Quaedfliegh on 11-07-2014 01:18
#9
ValerioW wrote:
Susan R Walter wrote:
Many thanks Reinoud. What characters should we be looking for? My friend who was with me has other photos we can check, but this is the best of mine. Or do we need specimens (which we don't have)?
First thing to do with any kind of arthropod, after you are sure about family is:
1)
determine the subfamily: with asilids useful tools are
overall shape (which helps to exclude Leptogastrinae...checking wing's alula or legs' pulvilli can be the best in this case),
antennae. (Laphrinae subfamily has no arista),
front tibia (i.e. spurs),
frons . Genitalia examination comes later, mostly for genus/species IDs.
?????????????
Susan asked about the characters that should be visible to make a definitive identification, she had more pictures. To me there is no doubt about the fact that these are Asilinae. As you mention the genitalia are important to identify the genus and/or species. As they are not visible i answered Susans's question with just that.
You refer to characters of subfamilies that these creatures obviously do not belong to (alula, spurs, pulvilli etc). They simply belong to the Asilinae there is no doubt about that. Especially when we know where the picture has been made.
I assume we can agree on Asilinae?
What can we see and where and when has the picture been taken.......
The picture has been taken in the central lowlands of France the Asilidofauna can be described as NW European and very similar to the Belgian and Dutch situation with some extra species.
-The mesonotum is not covered entirely with setae so we can exclude Dysmachus as genus.
-The legs are entirely black and shiny with mostly black bristles. (this excludes most other asilinae and we are left with Machimus setibarbis Machimus caliginosus and Eutolmus rufibarbis)
-Beard consists for a large part of reddish bristles below a few black ones. (rufibarbis!) we can exclude both Machimus species for they have basicly black beards with only a few light coloured bristles in the lower part)
-Mating takes place head to head as Eutolmus rufibarbis does and so even excluding all other subfamilies in NW Europe, which mate in opposite direction as do the the larger Machimus species generally)
Why am i 99% sure about Eutolmus? Because i've seen this species hundreds of times (its quite common in NW Europe), also in copula.(http://www.diptera.info/photogallery.php?photo_id=6043 in collection) also in the Loire area.
Edited by Quaedfliegh on 11-07-2014 22:02