Male P. sandaka.

This is one of those which can be rather confusing.
The grey band is much constricted, beaded & mostly disappear above & below.
The foot of the postdiscal band which runs along the lower margin (dorsum) is large & long.
There is a hint of the white speculum on the HW by the white line below the FW.

In P. hordonia the the grey band is broad & continuous &, the foot of the postdiscal band in the male smaller & shorter.
Typical wsf ,P. hordonia hordonia.
China.
https://farm6.static.flickr.com/5813...b8cd235a_b.jpg
Thailand.
https://wingscales.com/content/record/450-1-c2fd9.jpg
Raub Malaya.
http://4.bp.blogspot.com/-6TIVtGI_ok...0/DSC_0229.JPG
Taman Negara Malaya.
http://www.learnaboutbutterflies.com...nia%20001a.jpg

Forms with broad orange bands, dsf or partial dsf Thailand. Note grey band is a bit more restricted.
http://www.norththailandbirding.com/..._lascar_05.JPG
https://www.thaibutterflies.com/wp-c...a-1080x675.jpg

P. sandaka sandaka ,Raub, Malaya.
https://2.bp.blogspot.com/-c8rXTibfe...0/DSC_0137.JPG

TL Seow: Cheers.