Notice the male N. berenice here is unusual in that the dark striae within the postdiscal band are largely missing. This is normally a feature of the N. beroe male.
Here is a more typical male N. berenice with the dark striae very strong. http://www.butterflycircle.com/check...hee%20Beng.jpg
The first one is Ionolyce helicon. The wing shape and the post-discal striae on the forewing in space CuA1 give it away. I've shot many of these hoping that one of them would turn out to be N. beroe. N. beroe seems rare- i've not seen one yet.
There are several species recorded from Singapore in the past.
Nacaduba 4-lines with the dark striae absent or weak.
A. HW with the marginal & submarginal spots wider apart. 1. N. sanaya & 2 .pendleburyi.
B. HW with the marginal & submarginal spots near to each other 3. N. subperusia & 4. N. hermus.