jginieis's picture

3800 (male) Onychogomphus forcipatus 22082013

Observed: 22nd August 2013 By: jginieisjginieis’s reputation in Invertebratesjginieis’s reputation in Invertebratesjginieis’s reputation in Invertebrates
3800 (male) Onychogomphus forcipatus 22082013
Onychogomphus forcipatus (femelle)   22082013
Description:
Identifications
Species interactions

No interactions present.

Comments

jccurd's picture

I believe these are both O. uncatus

First of all, these are two different individuals. The 1st picture is a male and the 2nd picture is a female. the 2nd individual has a noticeably thicker abdomen and very different (simple, not hooked) anal appendages. You're better posting multiple photos separately unless you are quite sure they are of the same individual.

The eye colour of these characters is not very reliable.

Check out this DragonflyPix page, and particularly, hover over the "parallel black stripes" reference in paragraph #1. [BruceH: you pointed me at this helpful reference.]

This specimen shows the more parallel black shoulder stripes of O. uncatus, the innermost one of which does not meet the mid-dorsal stripe, as opposed to the more divergent black stripes of O. forcipatus which both do meet the mid-dorsal stripe.

A second indicator of O. uncatus is the yellow collar around the top front of the thorax which here is interrupted centrally by a black bar - not so in O. forcipatus. [See Dijkstra/Lewington, if you have one.]

Thirdly, this individual does not have a yellow bar in the black of the vertex (between the eyes) as O. forcipatus does.

Here's another good diagram.

Very nice catch, by the way. :))

John

RoyW's picture

A shorter ID discussion...

See the excellent 'annotated' images here: http://guillaume.doucet.free.fr/doc/uncatus_versus_forcipatus.jpg