Tanaecia in Singapore.

[Psyche]

This observation is interesting in that the FW arrowheads ,rendered in white are separated from the series of postdiscal spots to the inside.
https://www.inaturalist.org/observations/137292791
https://inaturalist-open-data.s3.ama...783/large.jpeg

In all the three other similar species in P. Malaysia the white area to the inside of the arrowheads are not separated as distinct spots.
T. pelea male.
https://inaturalist-open-data.s3.ama...253/large.jpeg
T. palguna male.
https://thaibutterflies.com/wp-conte...ia-palguna.jpg
T. munda male.
https://singapore.biodiversity.onlin...0485?imageId=1
T. aruna male.
https://thaibutterflies.com/wp-conte...ia-aruna-1.jpg
http://yutaka.it-n.jp/lim2/720930001.html

Tanaecia is very variable & the subspecies from nearby islands eg Sumatra ,Borneo are very confusingly different.

This looks almost certain to be T. aruna but one can not rule out a form of T. pelea say from Borneo, an escapee from a butterfly farm.
Better pix will help to confirm the ID.

TL Seow: CHeers.