[Odonata-l] Female Ophiogomphus ID Request

[Michael Blust]

Nick - I am curious about the apparent lack of relevance given to the dorsal spots on segments 8 and 9.  Walker uses this prominently in his key, but practitioners seem to be ignoring it.  Has this been found to be too variable?

It is also my sense that something like the post-occipital horns should NOT be highly variable if they are important for correct pairing in copulation.  Yet I get the sense they are not as consistent as the Enallagma mesostigmal plates etc.  Do these horns get broken off at times as well?  

Mike 

 

-----Original Message-----
From: odonata-l-bounces at listhost.ups.edu
[mailto:odonata-l-bounces at listhost.ups.edu]On Behalf Of
tdonelly at binghamton.edu
Sent: Tuesday, April 04, 2006 10:23 PM
To: Bryan Pfeiffer
Cc: odonata-l at listhost.ups.edu
Subject: Re: [Odonata-l] Female Ophiogomphus ID Request


Bryan - Ophiogomphus females are a challenge. The occipital horns are poor
characters.  They are highly variable, often absent, and commonly broken
off, esp. following cop.

The better characters are the POST occipital horns, if present, on the
rear of the head, and the subgenital plate.  The latter is fairly variable
also, leaving -  a mess.

I think your illustrations are of mainensis.

You should be alerted to the possibility of hybrids.  I have seen two
examples of carolux X rupinsulensis females from Massachusetts.

Nick
>
> Learning a lesson in humility, I'm embarrassed to report that I'm
> wandering
> the keys aimlessly on this female Ophiogomphus:
> http://www.wingsenvironmental.com/ophio.html
> She's from Vermont on 13Jul2005 (and lacking any post-occipital horns).
> Any wisdom would be most welcome. Thanks.
>
> --Bryan Pfeiffer
>
>
> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> WINGS ENVIRONMENTAL
> 113 Bartlett Road
> Plainfield, VT 05667 USA
>
> Ecological Inventories of Birds and Insects.
>
> Web:    www.WingsEnvironmental.com
> E-Mail: Bryan at WingsEnvironmental.com
> Phone: (802) 454-4640
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