There are distinct populations of the species in China with consistent differences in the extent of the darkened areas in the wing, so it is possible this is a superspecies, but until that is proved it is best to treat all populations as B. melanopteryx. The Vietnamese specimens all have the apical half of the outer wing blackish.
I know have also found B. serrata in quite a few additional locations to the spot north of Pia Oac where I first saw it last year. Apart from several sites around Pia Oac, it was also rather common close to Tu Le in Yen Bai Province and to my surprise I also ran into a female in Xuan Son National Park. Another addition to the already extensive list of that place. Earliest record this year was May 23 and latest was June 30. Apparently not so rare as thought.
|The very dark body of the male of Bayadera melanopteryx|
|Which becomes very easy to recognize once you see the wingtips. Bayadera hatvan has clearly darkened wingtips and Bayadera hyalina has slightly darkened tips, but never as extensive and clear-cut as in B. melanopteryx|
|The female of B. melanopteryx has similarly darkened wingtips, although not as dark brown as in the male. The thorax pattern recalls B. hyalina, but see the completely pale metepimeron.|
|In dorsal view the curved dorsal stripes are also very different|
|Here is the first of two photographed females of B. serrata. In patterning of the thorax very similar to the male. This one is from Pia Oac.|
|Whereas this one is the female from Xuan Son, found inside the forest not far from the main stream.|