Thread subject: Diptera.info :: Leucozona
Posted by Juergen Peters on 22-05-2005 22:24
#1
Hello!
I took this picture of a male
Leucozona yesterday here in Germany, but I'm not quite sure, where to look for the darkish hairs on the abdomen to distinguish between
L. lucorum and
L. inopinata. Can anybody help me? Thanks in advance!
Edited by Juergen Peters on 22-05-2005 23:28
Posted by Gerard Pennards on 23-05-2005 09:28
#2
Hello Juergen,
To distinguish between Leucozona lucorum and L. inopinata, you have to look at the side margin of the 4th abdominal segment, called tergite 4!
In L. lucorum tergite 4 has predominantly white hairs, with some black hairs in the middle of the tergite. In L. inopinata tergite 4 has dark hairs, also along the side margin. The other difference lays in the percentage of very small hairs in a certain cell in the wing, but without magnification difficult to see!
So, having said this, it it clear to see from the upper picture that this is a male of Leucozona inopinata!
Greetings,
Posted by Juergen Peters on 23-05-2005 18:19
#3
Hello, Gerard!
Gerard Pennards wrote:
To distinguish between Leucozona lucorum and L. inopinata, you have to look at the side margin of the 4th abdominal segment, called tergite 4!
In L. lucorum tergite 4 has predominantly white hairs, with some black hairs in the middle of the tergite. In L. inopinata tergite 4 has dark hairs, also along the side margin. The other difference lays in the percentage of very small hairs in a certain cell in the wing, but without magnification difficult to see!
Thanks for your explanations! My main problems seem to be a) to tell which hairs are really dark or only seem to be so because of the dark background and - more serious - b) to identify tergite 4 :-(. Counting from the thorax I looked at the tergite no. 2 for the dark hairs (see arrow). Or have I to count from the back end (in- oder excluding the small final segment)? Also, the numbering seems to be incongruent between the different insect orders. Not the end of my difficulties: additionally the original 11 segments are redeveloped or fused in most higher insects... :-/
Posted by Gerard Pennards on 23-05-2005 21:51
#4
Hello Juergen,
Well, in Syrphids it is like this: (by the way, you start counting from the thorax to the end of the abdomen) the first abdominal segment is always very small and hardly visible, so the first bigger segment you see is number 2!
So, in your picture with the arrow, the tergite you call 2 is in reality tergite 3! So you have to look one tergite beyond that one.
And then you have to look at the hairs at the side margin of that tergite. The color of the hairs is not that difficult, in L. lucorum it is very well visible as silvery white, whereas in L. inopinata they are really black!
Greetings,
Posted by Juergen Peters on 24-05-2005 03:53
#5
Hello, Gerard!
Gerard Pennards wrote:
So, in your picture with the arrow, the tergite you call 2 is in reality tergite 3! So you have to look one tergite beyond that one.
And then you have to look at the hairs at the side margin of that tergite. The color of the hairs is not that difficult, in L. lucorum it is very well visible as silvery white, whereas in L. inopinata they are really black!
Thanks again for your explanations. Now I see! Will check my other
Leucozona pictures for the difference.