C. vietnamicus. FW subapical spots separate FW band outer margin (in some both margins) notched about 90 degree at vein 2. http://yutaka.it-n.jp/hes/90551001.html
5. C. leucocera FW band w3ith a small extension towards the costal margin.
HW cilia outwardly white & basally yellow, chequered at the veins. http://yutaka.it-n.jp/hes/90470001.html
C. putra;FW band without an extension above the radius (upper arm of FW cell) to the costa.
HW cilia whitish chequered at the veins.
FW produced, sharper. http://yutaka.it-n.jp/hes/90480010.html
Post 4.
Hong Kong have only one species, C. leucicera. so this is correct.
The typical form as described by Evan is as in post 1 image 5.
ie.
FW white discal spots/band with a small extension above the radius.
HW cilia outwardly white & basally yellow.
2. matches C. oscula correctly, inparticular the 3 subapical spots , spot 6 & 8 very large & spot 7 very small.