May 31 and June 1 I was in Xuan Son National Park and encountered many smallish Idionyx females, all females, scurrying around in semi-secluded areas in the forest or at darker moments in slightly more open places. They all had in common that they had a very bright light-yellow labrum and smoky wings. The also had short antehumeral stripes. With I. thailandica / victor they shared lateral thorax pattern and a rounded vertex. But that facial pattern, those dorsal thorax markings and smoky wings… Actually I am still a bit at a loss here. But checking Asahina I found that his description of Idionyx selysi fits the present species well. The combination of bright-yellow labrum and anteclypeus, the lateral thorax pattern with a characteristic bite out of the posterior margin of the second dark lateral stripe, the brownish wings, the rounded frons, the small vulvar lamina forming a simple crest, this all fits well. The legs seem oddly dark though, and the anal loop has too many cells. But for the moment and until I catch a male, I think this is the safest bet. I am not aware of any Idionyx species in the region that has such brownish wings. But maybe someone has another suggestion. In the meantime, let's find the male!
Idionyx selysi occurs widely in Lao PDR, in Thailand and Myanmar. It is suggested that its occurrence in Vietnam should not come as a surprise.
|By the looks of it: Idionyx selysi|
|For comparison. I thailandica. Note slightly different thorax pattern, S1-2, yellower tibia and of course wing color|
|Face of I. selysi (?) with very light-yellow labrum and anteclypeus.|
|Thorax pattern, showing the short antehumeral and the dent in the posterior edge of the dark stripe over the metapleural suture towards its dorsal end.|
|Scan in dorsal view, note many more cells in anal loop|
|I. thailandica for comparison|