This is not Arbudas leno - a species that is not recorded in Hong Kong, and is actually placed in the genus Pidorus according to Endo & Kishida (1999). The actual identity of this is "Pidorus" gemina, though the generic placement is under review by Yen Shen Horn (National Sun Yat Sen University, Kaohsiung).
Endo, T. & Kishida, Y. 1999. Day-Flying Moths: Chalcosiinae. Epicopeia. Endless Collection Series vol. 8. Endless Science Information, Tokyo.