Thread subject: Diptera.info :: Gomphus simillimus

Posted by Rui Andrade on 04-02-2008 20:06
#1

I found these two specimens in Barcelos, Portugal. The first photo was taken on the 4th of June 2006 and the second on the 20th of June 2006. I think they belong to the same species, maybe a Gomphus species?

img246.imageshack.us/img246/3448/gomph1sx9.jpg

img238.imageshack.us/img238/4716/gomph2wy1.jpg

Edited by Rui Andrade on 05-02-2008 17:43

Posted by Susan R Walter on 04-02-2008 20:36
#2

Rui

These are Gomphus simillimus, female.

Posted by Rui Andrade on 04-02-2008 20:52
#3

Thank you Susan.

There are other very similar species, so if you could explain me the characters you recognized I would be very grateful.

Posted by Susan R Walter on 04-02-2008 22:52
#4

The main confusion would be with G flavipes and G graslinii I think. I am not actually familiar with G flavipes in the field, but Dijkstra and Lewington make the distinctions pretty clear. A good quick clue that this is G simillimus is that it has the combination of black and yellow striped legs and the black markings on the top of the thorax do not join up to enclose a yellow oval.

G vulgatissimus
- completely black legs - your photos show yellow and black stripey legs.

G graslinii - yellow antehumeral stripe clearly narrower than the black ones. Your photos show all three stripes much the same width.

G flavipes - the yellow antehumeral stripe continues uninterrupted to the legs. Your photos show the black antehumeral stripe dividing and terminating the yellow stripe.

The features I've mentioned above as visible in your photos all fit G simillimus.

Posted by Rui Andrade on 04-02-2008 23:54
#5

Thanks a lot, you really helped me out on this one!:)

Posted by Christine Devillers on 05-02-2008 13:31
#6

Another easy feature between flavipes and simillimus:

G simillimus : The yellow antehumeral stripe is clearly narrower than the dorsal yellow band

G flavipes : The yellow antehumeral stripe is about the same width than the dorsal yellow band

Posted by Rui Andrade on 05-02-2008 17:41
#7

Thank you Christine for the extra info.:)

Posted by Susan R Walter on 05-02-2008 20:35
#8

Christine

This sounds like a good tip, but I am not clear about which dorsal yellow band you mean. Could you explain please? I've never seen G flavipes, but it would be possible for me - they are along the Loire.

Posted by Christine Devillers on 05-02-2008 23:43
#9

I have taken the first picture of Rui to explain.

Posted by Susan R Walter on 06-02-2008 15:07
#10

Ahh! Excellent, thank you very much. That would be quite easy to see in the field if the beast was resting.