There is no doubting this specimen as H. chalcedonyx since everything matched.ie. white foreleg, FW white spot with an extension below vein 2 into space 1b; brown wings with basal blue.
It is difficult to differentiate the two species based on the underside.
All perceived differences in the past are partly incorrect because of variation.
In hindsight, I would say your post 1 pix 2 is likely H. chalcedonyx as well.
Probably all those in KPN are H. chalcedonyx too.
They do look somewahat like the pix of H. albimacula from HK but post 24 shows the underside FW white spot also extends broadly below vein 2 , although how far down is uncertain.
There is some variability in albimacula here.
India. Note the white spot extends broadly if diffusely below vein 2. (Not sure why taxon viola is elevated to full spp.)
http://www.ifoundbutterflies.org/med...aDas_ap237.jpg
HK. This is more typical where the extension below vein 2 is poor.
http://old.hkbutterfly.org/images/Horaga_albimacula.jpg
In any case, only the upperside can provide a definitive diagnosis.
TL Seow