Tuesday, 23 December 2014

Epophthalmia frontalis - this is what makes me tick

On November 13 we were checking the fishponds in Cat Tien. A large Cruiser-type dragonfly was doing the rounds on one of the ponds. I was able to make a few vague inflight shots. Enough at home to see that it was one of the southern Epophthalmia types. But which one? Vittigera, vittata or frontalis? It was only a few days later that I could catch two males and on the 17th I caught also a female. Facial pattern and appendages quickly ruled out vittigera, but the literature on vitiate/frontalis is less straightforward. The yellow spot on cleft in front of the vertex is restricted to the cleft, says Fraser (1936), and separated into two round spots in frontalis. But Asahina (1969) does not make that distinction. His drawing of male frontalis has exactly the same spot as our specimens. It is not altogether clear whether these two species are truly different, rather then geographical variants. If so, E. vittata is the senior synonym. But appendages of male, lamina of female, facial pattern all fit perfectly with E. frontalis, so for the time being I settle on that species. James Holden had reached the same conclusion already before, when he had seen the species in the summer. Although it had been absent in August, it was quite common now, with several males on the same ponds.

First few record shots. Note the reddish-brown abdominal tip.
Another record shot of the same individual
One a two males caught. In E. vittigera the superior appendages have quite a different shape. This is the male of E. frontalis.
Another male of E. frontalis.
The male face with large yellow spot in the cleft, yellow spots on either side of the frons , cream-white undulating line over the postclypeus and cream spots on the bases of the mandibles and on the labrum.
The face of the female is somewhat different, in that all marks are in yellow and there are only two spots on the postclypeus.
The fantastic female, note the dark wing bases.

Distintive brown appendages, superiors shorter than epiproct.

And in dorsal view, appendages slender and relatively straight.

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