[Odonata-l] Fwd: Ophiogomphus head damage

Tue Mar 25 05:42:36 PDT 2008

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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