Forum Entomologi Italiani

L'ho fotografato questa mattina alle Saline di Cagliari? E' lui?
Grazie a tutti.

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Se gettassi su di un piatto della bilancia tutto ciò che ho imparato a comprendere in quelle ore di meditazione di fronte all'acquario, e sull'altro tutto ciò che ho ricavato dai libri, come rimarrebbe leggero il secondo!
Konrad Lorenz

I will stop Orthetrum coerulescens (Fabricius, 1798).
At least in theory an mature male of Orthetrum coerulescens anceps will have also the thorax all pruinose almost like O.brunneum.

cosmln

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Cosmin-Ovidiu Manci
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cosmln's place - my blog
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Dragonflies of Romania

but cosmln there is a wide variability on that character alone, as much as several intermediate specimens too... Also, I find several intermediate looking males in secondary genitalia structure...
In Sicily, where supposedly there is also anceps, it is also known to occur an intergrade (clinal?) population...
Indeed, I never found so far any "anceps" perfectly fitting the original description here, but a huge series of odd looking one. Further, the thorax here could appear any range of colour from browinish to yellowish to pruinose, but almost never seen any of them with a brunneum-like colour, not even close...only few very mature males with pruinosity almost same shade and hue of S1-S7 (with colour of segments S8-S10 not quite visible due to female scratching) ...

However, in Sardinia, acconding to data known, there should be only anceps... indeed, therefore, better and more in depth studies should be done....

I think Doc Gomphus would put light on that and help us understanding better....

Ciao

Andrea

I think that I have from Portugal some very blue specimens, I'm not referring at the more darker color of O.brunneum only that ussualy mature males are more or less like O.b. covered almost completely with pruinosity.

And like you said to say something sure in this case you need to have specimens in hand (or photos of genitalia)... at least I will not say after this photo that is anceps... don't have yet that knowledge (and don't think I will have that).

cosmln

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Cosmin-Ovidiu Manci
**********************
cosmln's place - my blog
just insects
Dragonflies of Romania

Thank you very much Cosmin and Andrea .

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Se gettassi su di un piatto della bilancia tutto ciò che ho imparato a comprendere in quelle ore di meditazione di fronte all'acquario, e sull'altro tutto ciò che ho ricavato dai libri, come rimarrebbe leggero il secondo!
Konrad Lorenz

hi

the deep blue colour of the thorax (although, as far as i know, never exactly as intense as on abdomen, unlike O. brunneum) is characteristic of exceedingly old individuals, not only in anceps, but also to be found in coerulescens coerulescens; anyway, this is not yet fully coloured

a remark: fully pruinose males (as well as fully coloured red or black males of other libellulids) are usually qualified as "mature", yet this is not correct; full colouring and maturity are not exactly synchronous, conversely maturity may predate definitive colouring, i have several times observed not fully pruinose (with abdomen only incompletely pruinose, and thorax not at all) mating coerulescens males, and the same for not yet entirely black Selysiothemis males

i have actually found the "true" anceps only in sardinia; these animals have accessory genitalia at S2 with lamina anterior only a little longer than hamuli, nearly straight and distinctly tapering at apex, somewhat blade-like

conversely, animals from sicily (where, indeed, i have found no great variations, they looked more or less all the same), although generally they are referred to as anceps, appear somewhat intermediate between typical coerulescens and anceps; again they have lamina anterior only a little longer than hamuli (not much longer as in coerulescens) and nearly straight (not distinctly bent forwards at mid-length), yet the swollen apex is more similar to coerulescens than to anceps

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maurizio

just a few photos showing a little of the wide variability in Sicilian males.... note please from almost yellowish to rather pruinose, with also variability connected to the pattern and legs colour. Also note the secondary genitalya as described by Doc Gomphus....
Also, I've attached a PDF about this issue, though in a lenguage not so easy ...to me at least

ciao

A

Thanks again for further clarification.

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Se gettassi su di un piatto della bilancia tutto ciò che ho imparato a comprendere in quelle ore di meditazione di fronte all'acquario, e sull'altro tutto ciò che ho ricavato dai libri, come rimarrebbe leggero il secondo!
Konrad Lorenz