[Odonata-l] Fwd: Ophiogomphus head damage

Tue Mar 25 14:56:27 PDT 2008

Just to go on a bit about head damage.  There are numerous examples to the
front and top of heads.  The occipital spines of several genera are commonly
broken off, presumably during tandem pairing.  This is definitely an "ouch"
experience for the male!

The eye damage reported by Dunkle for Hagenius occurs also on other North
American gomphids.  I have seen good examples in Gomphus adelphus, for
example.  In Hagenius it appears to have been caused when the male epiproct
which is loosely "locked" in front of the female poct-ocellar tubercles
slips off and gouges the eyes.  Certainly measurements fit this explanation.
I guess that this sort of damage will be found to be somewhat common.

But the damage I report in Ophiogomphus is far from incidental.  I believe
it is found in the majority of mature females.  Teneral specimens, of
course, have the rear of the head quite unmarked and pristine.  Most mature
females have the rear of the head quite scraped and squeezed, which I guess
is caused by the male cerci.

By the way, I have long admired Pinhey's paper on this subject, which I do
not recall includes damage features.

Nick Donnelly

  _____  

From: odonata-l-bounces at listhost.ups.edu
[mailto:odonata-l-bounces at listhost.ups.edu] On Behalf Of Dijkstra, K.D.B.
Sent: Tuesday, March 25, 2008 8:43 AM
To: Odonata-l
Subject: Re: [Odonata-l] Fwd: Ophiogomphus head damage

An inspirational paper (on diversity of odonates: the incredible complexity
of their morphology, behaviour, taxonomy...) with lots of examples and
illustrations of how anisopteran heads and appendages (might) interlock was
written by the great Elliot Pinhey. Most, but not all, examples are from
African gomphids. Some examples show 'head damage', although I don't recall
if Pinhey realised that such holes were male-inflicted (e.g. it is common on
the female vertex in the genus Notogomphus):

Pinhey, E., 1969. Tandem linkage in dichoptic and other Anisoptera
(Odonata). Occasional Papers. National Museum of Southern Rhodesia (B) 4:
137-207.

Cheers, KD

________________________ 

Klaas-Douwe 'KD' B. Dijkstra 
National Museum of Natural History Naturalis 
P.O. Box 9517, 2300 RA Leiden, The Netherlands 

science.naturalis.nl/dijkstra 
barakken.nl/kddijkstra 
flickr.com/photos/kiskadee 

-----Oorspronkelijk bericht-----
Van: odonata-l-bounces at listhost.ups.edu
[mailto:odonata-l-bounces at listhost.ups.edu]Namens Dennis Paulson
Verzonden: vrijdag 21 maart 2008 22:51
Aan: Odonata-l
Onderwerp: Re: [Odonata-l] Fwd: Ophiogomphus head damage

Nick, I haven't seen the marks you speak of, but I'll have to look for them.
If they are on Ophiogomphus, I assume they are on other genera.

When you look at the hooks and bumps and spines on the appendages of many
male odonates, it's not surprising that there is female head damage,
especially when you think they have to hold on pretty tightly when they're
flying around in cop. I suppose all the little bumps and spines under the
cerci of many libellulids are sort of a nonskid apparatus, but do they leave
marks on the females? The cerci of species such as Arigomphus cornutus and
Octogomphus specularis look like lethal weapons. Do they leave bigger scars?
Philip Calvert described in detail the hooking up of the complicated
appendages of male Epigomphus with their females (Calvert, P. P. 1920. The
Costa Rican species of Epigomphus and their mutual mating adaptations
(Odonata). Trans. Amer. Ent. Soc. 46: 323-354.). At the same time, as it may
not be in the female's best interest to have her head pierced, you'd think
her cuticle would be strengthened at those points. Or is there some positive
consequence of the "mating marks" on females, for example those on the eyes
of aeshnids that Sid Dunkle described (Dunkle, S. W. 1979. Ocular mating
marks in female Nearctic Aeshnidae (Anisoptera). Odonatologica 8: 123-127.)
and can be found on a variety of female anisopterans?

To me an interesting question is why cerci should have spines or hooks on
the dorsal surface, which presumably doesn't contact the female. Does the
projection on the top of the cercus in something like Epitheca canis serve
any function? Does it touch the female somewhere? Mark McPeek is doing all
this interesting scanning of cerci in damselflies, but I think someone
should be looking more closely at the situation in anisopterans as well.
Mating pairs of anisopterans should be collected and somehow preserved in
tandem, even with the female's head detached from her body. As the
connection is only on the head, it might be easier to understand than the
perhaps more complex connection of male zygopteran appendages with both the
female prothorax and mesostigmal laminae. And we need a good assessment of
the sensillae that are presumably present in the female to tell her that the
male appendages "feel right."

When I see the amazing amount of variation in the complicated appendages of
male odonates, I often wonder how those of each species could possibly hook
up to the female's head or thorax and whether the varied shapes are a
consequence of selection for reproductive isolation or a varied response to
holding on tightly. Within a genus of libellulids, the appendages are often
fairly similar, but then they may be quite different in another genus. Why?
Some adaptations seem obvious, like the long, simple cerci of male Tramea,
used for quick reattachment to the female after each oviposition dip. Most
others aren't so obvious.

On Mar 21, 2008, at 2:27 PM, Dennis Paulson wrote:

Begin forwarded message:

From: "Nick and Ailsa Donnelly" <tdonelly at binghamton.edu>
Date: March 21, 2008 2:09:18 PM PDT
To: <dennispaulson at comcast.net>
Subject: To be posted on the list serve

Damage to rear of female heads of Ophiogomphus.

Recently I have been removing the heads of several species of Ophiogomphus
to examine the rear.  I have noticed some damage, which I can best describe
as crude near-vertical elongate indentations, usually with small scrape
marks.  I first thought these were something I was doing while removing the
heads, but I now think that they are older, and probably existed during the
life of the female.  Perhaps the pressure of the cerci (which lie on th
erear of the head) is more important than I had thought in maintaining the
grab of the close-fitting eprproct on the face.  Has anyone ese wondered
about these marks?

It seems pretty clear that tandem pairing removes most of the hairs on the
female occiput by rubbing (teneral females are quite hirsute, but older
females have few hairs left), and I believe the horns on the occiput are
often broken right off.  But these marks on the rear of the head baffle me,
unless they are the marks left by  the medial edge of the cercus.

Nick Donnelly

-----
Dennis Paulson
1724 NE 98 St.
Seattle, WA 98115
206-528-1382
dennispaulson at comcast.net

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