Which Horaga?

Horaga onyx sardonyx.

Of the four similar species they can be group into two.

The smaller H. albimacula & chalcedonyx have the foreleg tibia mostly white

H. albimacula have the FW white patch large like H. onyx. Upperside brown. Upperside FW white patch ends at vein 2.
http://thaibutterflies.com/wp-conten...albimacula.jpg
HK
http://hkcww.org/hkmoth_butterfly/readid.php?id=5865

H. chalcedonyx have the FW white patch narrower & upperside is marked with blue scales. Upperside FW white patch extends below vein 2 into space 1b.
http://yutaka.it-n.jp/lyc4g/83173020.html

Additional note The only consistent difference in underside (based only on a couple of valid specimens each) is in H. albimacula. the FW white spot tend to be wider & its outer border have a mid angulation with a notch.
In H. chalcedonyx the white spot is narrower, its outer border regularly convex.

The two larger species H. syrinx & onyx have the foreleg tibia banded as the rest.

H. syrinx maenala.
The FW white patch is typically narrow. (In some ssp. broad as in onyx)
HW postdiscal band ,the narrow part after the bend is undulate, variously thicken & reaches vein 1a but not the margin.
http://www.butterflycircle.com/check...ark%20Wong.jpg
http://www.butterflycircle.com/check...20-%20Khew.jpg
http://www.butterflycircle.com/check...04_02_2011.jpg
http://www.butterflycircle.com/check...20-%20Khew.jpg

http://yutaka.it-n.jp/lyc4g/83170010.html

H. onyx sardonyx.
FW white patch is typically broad.
HW postdiscal band after the bend is mostly straight on its upper /inner black-edged margin .& runs past vein 1a to very near the margin (dorsum)
Thailand.
https://thaibutterflies.com/wp-conte...x-1080x675.jpg
India.ssp onyx.
https://www.ifoundbutterflies.org/me...ekar_ag359.jpg
P. Malaysia.
https://inaturalist-open-data.s3.ama...jpg?1578210772

Singapore. This image is also in NSS.
https://farm4.staticflickr.com/3480/...fac_z.jpg?zz=1

http://yutaka.it-n.jp/lyc4g/83160010.html

TL Seow: Cheers.