Sunday, 3 May 2015

Atratothemis reelsi - new for Vietnam

2-3 May I travelled to Mau Son with Haruki Karube and small party of Japanese students. In the afternoon I walked to the end of the trail that does not bent down to the village on the slope and by-passed a pool on the left side that looked in pretty bad shape, muddy and green in places. Although fed by a seep and probably originally a nice natural pool, it now is visited frequently by a group of water buffaloes. That does the water quality no good. But there were several species flying about, so I looked and my attention was drawn by a fluttering dragonfly with large blackish wing patches. In a way it reminded me of flying Dysphaea basitincta, but of course that was not it. When it perched it seemed to be a Rhyothemis, but not a species I knew. Later checking the literature I thought it might be Rhyothemis severini, although it is not blueish, but all brownish black in the wing. The apical spots in the wings were more distinct as well. Haruki collected a male for DNA research, to check whether it is in fact maybe distinct from typical R. severini. This was the status quo and I first published this here on the blog as the rediscovery of R. severini, 116 years after it had been described by Ris on the basis of a single specimen, collected in 1899, from "Indochina".  We considered this a very exciting turn of events. However, the starting assumption that this was a Rhyothemis was wrong. Luckily a reader of my blog pointed towards the solution, a solution that explains the differences in patterning with R. severini. It is a different species called Atratothemis reelsi, a little known libellulid described by Wilson in 2005 and known from Guangxi, Guizhou and Hainan in China and likely also occurring in Lao DPR. This is supported by the characteristics of its wing venation and secondary appendages. The occurrence of 2 males at a muddy hole at 1000m altitude was a huge surprise if it had been R. severini, but may fit Atratothemis reelsi better, although next to nothing is known about its habits.

Atratothemis reelsi, with typical large apical spots and large blackish basal marking in hindwing bordered along trailing edge by whitish cells. 

No blue shine whatsoever, as would be expected in Rhyothemis severini.

Specimen in lateral view

The fantastic blackish brown insect in dorsal view. Note the undulation of R3, the many cross veins in the bridge and the three-celled triangles in FW and HW. It does have even more cross veins in the cubito-anal spaces than described for the genus by Wilson (2005)

4 comments:

  1. Couldn't this be Atratothemis reelsi?

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    1. Excellent suggestion! In fact, that would seem to be the perfect solution. We did not think of that at all, but clearly that explains the differences in colour pattern! I will adjust!

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    2. I'am glad that I could give you an indication. Your blog really is spectacular, with so many excellent pictures of exceptional dragonflies, probably published for the first time!

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  2. Thank you! I cannot see your name on the postings. Can you perhaps introduce yourself? Anyway, thank you for the support.

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