Friday, 27 June 2014

Drepanosticta revisited - a new species after all*

*This entry adjusted August 8, 2018. The new species described below has been published by Dow & Kompier (2018) as Drepanosticta emtrai.

Today, June 27, I had a home day, during my 3 week survey of Northern Vietnam. But of course I could not stay in, so I went for a short trip to Hoa Binh Province, to a touristic site Sebastien introduced to me. Sorry to say, I hated it, but while I was there I noticed a female Coeliccia that was big and had the colors of C. uenoi. That would be a great discovery, so I looked around for the male. I did not find it. But while doing so, I noticed a Drepanosticta. It looked as it was supposed, dark thorax, small rings on dark abdomen, blue abdomen tip. All the works of D. hongkongensis, see the other blog entry on that species. Nevertheless, in hand the appendages appeared different and because it was a new location, I ventured to take it with me. Ba Vi is of course not that far from Hoa Binh, but far enough. When I got home I checked it under the microscope and lo and behold! It showed the same lobe on the superior appendage as the specimen from Ba Vi I took pictures of last year and now, after seeing a great many D. hongkongensis, had sort of dismissed as aberrant (see the first Drepanosticta entry). There are in fact many differences in the appendages, apart from its slightly smaller size, and like I thought of last year's specimen, it has blue markings on the prothorax and also a small blue mark at the base of the second pair of wings. There can be no doubt, this is a different Drepanosticta species and the same as that encountered last year on Ba Vi mountain. Clearly, there are two species in that forest, possibly one appearing earlier (May) and the other later (June/July)!

The two species side by side. On top is Drepanosticta hongkongensis, albeit larger than originally described by Wilson and with pale anterior lobe to the prothorax. In this scan a preserved specimen was used for comparison, so it is slightly duller than in real life. The bottom specimen is the new species from Hoa Binh. It is marginally smaller.

Appendages of D. hongkongensis in dorsal view. Note the blunt tooth to the inferiors.
The same for the new species, note the acute tooth, slanted posteriorly.
Ventral view of appendages of D. hongkongensis. Note the blunt tooth to the inferiors and absence in this view of a process to the superiors (which in fact have a small process, as can be seen in dorsolateral view).
The rather differently shaped appendages of the new species (Drepanosticta emtrai). Dorsum of superiors smoothly rounded and large ventral process at 3/4th of length of superiors.

In dorsolateral view a small process can be seen in D. hongkongensis on the inside of the superior appendages.

This is clearly much more prominent in the new species (Drepanosticta emtrai)

Ventral view of appendages of D. hongkongensis. Note almost straight outer edge of inferiors, that smoothly bend inwards towards the tip.

This is very different in Drepanosticta emtrai. At the halfway point (where the acute tooth can be seen) the appendages make a clear bend outwards and curve almost semicircular back inwards again.

The prothorax shows blue on the lateral lobes and on the anterior lobe.

Here in view of the complete thorax blue can also be seen at the bases of the wings, notably the second pair.

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