1 to 4. Nacaduba hermus.

The 4 line blues can be quite difficult

N. hermus;
Dark striae within the bands obsolete or nearly so.
HW tornal black spot with a variable amount of metallic scales in it.
https://www.ifoundbutterflies.org/me...unte_ai927.jpg
https://www.ifoundbutterflies.org/me...gale_ah293.jpg

N. pactolus.
White striae often broaden.Tornal black spot with metallic scales.
HW submarginal spot 6 strongly angular , with spots 3, 4, %. with their inner margin straight.
https://www.ifoundbutterflies.org/me...kare_aq959.jpg

N. pavana.
Tornal black spot with metallic scales.
Dark striae within the bands strong.
https://www.ifoundbutterflies.org/me...7b4b4568-2.jpg

N. sanaya.
Tornal spot no metallic scales.
HW submarginal & postdiscal spots in space 34 & 5 well separated.
https://www.flickr.com/photos/33212211@N00/38717338791
Singapore
https://www.besgroup.org/wp-content/...i-LenaChow.jpg

N. subperusia.
Tornal black spot without metallic scales.
HW submarginal & postdiscal spots in space 4 & 5 close &/or touching.
https://3.bp.blogspot.com/-CCzm1ZlQs...rusia+lysa.jpg
https://thaibutterflies.com/wp-conte...a-1080x675.jpg