Saturday, 4 July 2015

Indothemis carnatica - easily overlooked?

Last year summer James Holden did a survey of dragonflies in Cat Tien National Park. I joined him for a bit and later revisited to expand a little on his work. One interesting species he found was Indothemis carnatica. In fact I failed to recognize the species when he showed it to me on photos and assumed it was Trithemis festiva. But James looked into it further and eventually solved the puzzle. In retrospect a clue to its identity was that it was seen at the deserted swimming pool in Cat Tien, a choice of habitat that does not suit T. festiva well, as that species prefers running water.

This spring Natalia von Ellenrieder et. al. published an article on their records in northern Vietnam, including Cuc Phuong National Park, and in it record I. carnatica from two locations in the park, the large lake in the middle and the abandoned swimming pool near the end of the central road. There is a pattern here…

Even though these records constitute the first for Vietnam, the choice of habitat indicates that it readily occupies new areas and / or ponds that combine relatively clean, but deeper water with rocky or stony surroundings.

Superficially they can easily be mistaken for the common T. festiva. Not only is it similar in coloration and shares a brownish basal patch to the hindwing, but it also has the habit of hovering over water or perching on nearby rocks or vegetation. If you google T. festiva you will find several misidentified I. carnatica amongst the photos. This indicates it may not be as rare as thought.

According to IUCN this is a little known and scarce species, but in fact this may partially be because it is overlooked.

Anyway, on June 16 part of my mission to Cuc Phuong was to see the species for myself, after having overlooked it in Cat Tien. In the middle of the morning I found several males over the abandoned swimming pool. I did not see any females. When it became too warm most species withdrew from the pond and so did I. carnatica.

Indothemis carnatica, male. Note the black-and-blue pattern on the abdomen and pale appendages.

Another photo of the same specimen
The same specimen up close in hand.
The male has a characteristic bulge on its lower belly (posterior on its venter, so to speak)


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