The two species Curetis saronis & tagalica are near identical & the only feature given to separate them are the leg colour.
In C. saronis the legs are banded red.
In C. tagalica the legs are banded black.
A recent observation have the male with dark grey-banded legs, with no trace of redness, suggesting C. tagalica.(Note also antennae not tipped orange.) https://www.inaturalist.org/observations/179106996
Years ago Federick shot a male with dark grey banded legs feeding on Noni flower ,Morinda citrifoloia.
Also there was a shot of a mating pair, the male with black-banded legs & the female with red-banded legs.
The population of C. saronis in Singapore seem to have legs banded variously from orange to red to dark brown.
It is possible some colonies may be of mixed origin.
Fleming in fact described C. tagalica as having legs banded dark brown or black.
Unfortunately there is no other shot with a better resolution for scrutiny.
C. tagalica was in the past recorded from Singapore.