Saturday, 7 December 2013

The female Paracercion ambiguum from Huu Lien*

*This post adjusted after publication of Paracercion ambiguum

This December 7 we went once more to Huu Lien, battling the traffic on "Highway" 1 and once again surviving. The objective was again to find the female of Paracercion ambiguum. The sun was only remotely present; it was rather misty and later on cloudy. We also got the distinct impression that numbers had dropped drastically. But I was in luck. I noticed a female damsel sitting on a stalk of grass emerging from the reservoir right by the grassy edge and was able to catch it. It was rather different from the females of P. microcephalum from last week. In fact, it had the sides of the thorax like the male, same pattern, but different colors. It was slightly larger than the male, with similar postocular spots, but the shoulder stripe was very Paracercion-esk. Close-up of the prothorax showed that it lacks the typical "horns" of Pseudagrion. So, is this not Pseudagrion after all, than what is it, as the male shows characteristics not really in line with Paracercion!

First some pictures of the female:

The female of Paracercion ambiguum, at last!

Close-up of the thorax. Note the same distinctive marking along the interpleural suture as in the male, the large postocular spots, but also the double light line along the humeral suture.

Now let's have a look at some other Pseudagrion prothorax and compare them with our specimen

Prothorax of female P. microcephalum, note the distinctive ridge and horns along the posterior edge.

In female P. rubriceps these are equally distinctive

Whereas in female P. spencei they are clearly visible, if not as large

But this distinctive Pseudagrion feature is missing from our species.

Here is an additional close-up of the ovipositor.

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