Nacaduba IDs needed.

Both are male Nacaduba berenice.

The 6-Line Blues may be ided thus.
Attachment 28538
A. Dark striae within the bands strongly developed in both sexes.

A1 Nacaduba berenice.
Upperside pale lavender blue in the male .Female pale blue.
UnF postdiscal band almost always dislocated or crooked or distorted in some way.
UnF submarginal spots variable, irregular.
UnF with a costal spot above the midcell band.
Males.
https://www.butterflycircle.com/chec...ce_male_01.jpg
https://www.butterflycircle.com/chec...obby%20Mun.jpg
https://www.inaturalist.org/observations/184357226
https://www.inaturalist.org/observations/161213020
https://static.inaturalist.org/photo...786/large.jpeg
Females.
https://www.butterflycircle.com/chec..._female_01.jpg
https://www.inaturalist.org/observations/152344058
Added.
https://www.inaturalist.org/observations/223317061
https://www.inaturalist.org/observations/81553866

A2 Nacaduba calauria.
UnF postdiscal band almost always straight or slightly curved.
UnF submarginal spots 4 & 5 mostly triangular & pointed.
Innermost costal spot present.
UpF dark violet blue in male; Female patch also dark violet.
Males.
https://www.butterflycircle.com/chec...--Jonathan.jpg
Male- left.
https://www.butterflycircle.com/chec...enry%20Koh.jpg
https://www.inaturalist.org/observations/215419158
https://www.inaturalist.org/observations/198791557
https://www.inaturalist.org/observations/86060926
Females.
https://www.butterflycircle.com/chec...yica---2--.jpg
Female- left. The male below is unusual in that FW spots 4 & 5 are blunt (hybrid element?)
https://www.inaturalist.org/observations/104467485

B. Dark striae within the band obsolete or weak in the male ;in female weaker than in group A.
Male FW margin rather straight.

B1. Nacaduba beroe.
UnF costal spot above the midcell band always absent.
UnF postdiscal band always with a mid or more dislocation.
Submarginal spots variable.
Male upperside deeper violet-blue; female FW patch darkish blue with white submarginal spots.
Males.
https://www.butterflycircle.com/chec...lt_male_01.jpg
https://www.butterflycircle.com/chec...ixLineBlue.jpg
https://www.inaturalist.org/observations/115695707
https://www.inaturalist.org/observations/109522376
https://www.inaturalist.org/observations/95242255
https://www.inaturalist.org/observations/95242254
Females .
https://www.inaturalist.org/observations/181540107
https://www.inaturalist.org/observations/160725153
https://inaturalist-open-data.s3.ama...323/large.jpeg

B2 Nacaduba kurava.
UnF postdiscal band almost always straight.
UnF submarginal spots mostly large with rounded margins. HW spot 6 similarly large
UnF costal spot above midcell band almost always present.
Male upperside deeper blue than berenice with see-thru underside markings ; female with FW blue patch whitened at apex.
Males.
https://www.butterflycircle.com/chec...ue-SunnyC2.JPG
https://www.butterflycircle.com/chec...neBlue-KSK.JPG
https://www.butterflycircle.com/chec...ze%20Siong.jpg
https://www.inaturalist.org/observations/126301432
https://www.inaturalist.org/observations/153437083
Females.
https://www.butterflycircle.com/chec..._female_01.jpg
https://www.inaturalist.org/observations/193867296
https://www.inaturalist.org/observations/77824453

Ionolyce helicon.
The males & females are sometimes confused with Nacaduba beroe.
Perpective distortion can drastically alter the wingshape.

Nacaduba beroe .UnH submargnal spot 3 (just beside the black tornal spot) is rounded.
eg females.
https://www.inaturalist.org/observations/73602464
https://www.inaturalist.org/observations/16479565

In Ionolyce helicon UnH submarginal spot 3 is always sharp pointed.
females.
https://www.inaturalist.org/observations/199863087
https://www.inaturalist.org/observations/202142216

TL Seow; Cheers.