<div dir="ltr">Dear All<div><br></div><div>There is some interesting reading in Reemer et al 2009. De Nederlandse Zweefvliegen'' in which the species Criorhina asilica is known to have both copulating positions, head-to-head and tail-to-tail. In Volucella bombylans there is another position, belly-to-belly adjacent to the head-to-head. So the rotation of the genitalia does not imply there is a fixed position in these species, and possibly this accounts for more Syrphidae.</div><div><br></div><div>Hope this helps.</div><div><br></div><div>Best wishes,</div><div><br></div><div>Jeroen</div></div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">Op wo 10 feb. 2021 om 17:04 schreef Francis Gilbert <<a href="mailto:Francis.Gilbert@nottingham.ac.uk">Francis.Gilbert@nottingham.ac.uk</a>>:<br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">
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<p class="MsoNormal"><span style="font-size:11pt;font-family:Calibri,sans-serif;color:rgb(31,73,125)">I do not think the degree of rotation in syrphid genitalia is fully understood yet. I don't
think it is the full 360 degrees of the Schizophora, but it is hard to be certain because of great confusion in the identification of the tergites and sternites of the postabdomen in syrphids, plus a lack of evidence.
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<p class="MsoNormal"><span style="font-size:11pt;font-family:Calibri,sans-serif;color:rgb(31,73,125)"><u></u> <u></u></span></p>
<p class="MsoNormal"><span style="font-size:11pt;font-family:Calibri,sans-serif;color:rgb(31,73,125)">Whether less than 360 degrees provides a bit of flexibility in mating position, I don't know.
Some end-to-end matings have the male upside down, whilst others they are both upright.<u></u><u></u></span></p>
<p class="MsoNormal"><span style="font-size:11pt;font-family:Calibri,sans-serif;color:rgb(31,73,125)"><u></u> <u></u></span></p>
<p class="MsoNormal"><span style="font-size:11pt;font-family:Calibri,sans-serif;color:rgb(31,73,125)">If Ximo's paper is correct and end-to-end requires a different kind of rotation, then those
syrphids mating like that should either have unrotated or even more rotated genitalia. However, Sphaerophoria is one of the ones that actually has been studied (Zaka-ur-Rab 1979) but unfortunately his account is also one of the hardest to understand, and probably
is full of mistakes.<u></u><u></u></span></p>
<p class="MsoNormal"><span style="font-size:11pt;font-family:Calibri,sans-serif;color:rgb(31,73,125)"><u></u> <u></u></span></p>
<p class="MsoNormal"><span style="font-size:11pt;font-family:Calibri,sans-serif;color:rgb(31,73,125)">The crucial evidence of rotation from internal anatomy (particularly tracheae, nerves and the
ejaculatory duct) are only available from Gäbler (who suggested only a 90 degree turn in Eristalis) and Griffiths (in "Syrphus", from serial sections, but not reported in detail). There is plenty of evidence from Schizophora of all three elements crossing
over in segments 7-8.<u></u><u></u></span></p>
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<p class="MsoNormal"><span style="font-size:11pt;font-family:Calibri,sans-serif;color:rgb(31,73,125)">Francis<u></u><u></u></span></p>
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<p class="MsoNormal"><b><span lang="EN-US" style="font-size:11pt;font-family:Calibri,sans-serif">From:</span></b><span lang="EN-US" style="font-size:11pt;font-family:Calibri,sans-serif">
<a href="mailto:syrphidae-bounces@lists.nottingham.ac.uk" target="_blank">syrphidae-bounces@lists.nottingham.ac.uk</a> [mailto:<a href="mailto:syrphidae-bounces@lists.nottingham.ac.uk" target="_blank">syrphidae-bounces@lists.nottingham.ac.uk</a>]
<b>On Behalf Of </b>ximo mengual sanchis<br>
<b>Sent:</b> 10 February 2021 15:30<br>
<b>To:</b> Hoverfly discussion list <<a href="mailto:syrphidae@lists.nottingham.ac.uk" target="_blank">syrphidae@lists.nottingham.ac.uk</a>><br>
<b>Subject:</b> [Syrphidae] Male genitalia rotation<u></u><u></u></span></p>
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<p class="MsoNormal">Dear all,<u></u><u></u></p>
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<p class="MsoNormal">this publication came out a couple of years ago, and since then, I wonder if Sphaerophoria or Ornidia (whose species copulate in an end-to-end position) are examples of "reverse evolution".<u></u><u></u></p>
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<p class="MsoNormal"><a href="https://phys.org/news/2019-02-evolutionary-rotation-genitalia-tied-success.html" target="_blank">https://phys.org/news/2019-02-evolutionary-rotation-genitalia-tied-success.html</a><u></u><u></u></p>
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<p class="MsoNormal">Any ideas? Maybe the authors were not aware of the diversity of positions in higher Brachycera...<u></u><u></u></p>
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<p class="MsoNormal">Ximo<u></u><u></u></p>
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