Sunday, 28 December 2014

Tetrathemis irregularis hyalina - the second Tetrathemis

During our second survey of Cat Tien National Park in November we encountered a great many of the lovely little Tetrathemis irregularis hyalina. This species had already been reported from Cat Tien and it was one of very few species reported and not yet found in the first survey and by James Holden. In August I did see just a couple of Tetrathemis platyptera, or so I thought. That made me somewhat skeptical concerning the occurrence of T. irregularis hyalina, but both species do occur in the same habitat. So, it should not have come as a surprise when we saw them all over the place this time round. Clearly it is absent during the wet season. We saw them along moderate slow and muddy streams and at pond and puddles in the forest. There was also one at the fishponds, so it tolerates a high variety of habitat. Although I was pretty sure I saw amber in the wings of the few females I saw in August, conditions were terrible, in the rain. Checking the photos, it seems that the size of the abdominal markings is in favor of T. irregularis hyalina, as is the color of the eyes. I apologize and correct myself...

Although very similar to T. platyptera, T. irregularis hyalina has completely clear wing bases (with large amber basal spots in T. platyptera)
Another male, perched by a pond
The neat facial pattern with pale-yellow anteclypeus and postclypeus and sides of antefrons.
The female of T. irregularis hyalina, with only limited markings on the abdomen compared to female T. platyptera.

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