The cleander group of Arhopala.

[Psyche]

The cleander group
FW postdiscal band spot 4 in line with the rest (ie spots 5, 6, & 9 above & 1b, 2, & 3 below.)
HW spots 5, 6, & 7 in echelon, 5 & 6 staggered & spot 7 atop spot 6.
HW postdiscal band completely dislocated at vein 2.(next to the V-shaped spot 1b.).
FW spot 10 is usually present.
The group is split into 2 subgroups.

The cleander species subgroup comprises two large species A. athada & silhetensis.

The alea subgroup comprise species which are about half the size of the cleander subgroup.

The cleander subgroup.
A. silhetensis is recognizable by its large size, & widely-spaced markings.

A. athada is variable in size & the smaller sizes may be mistaken for an alea member.
A useful guide is that in A. athada the HW postdiscal & submarginal spots/bands are well-separated from space 6 to the inner margin (dorsum).
A. athada showing wide separation between the two mentioned bands.
https://inaturalist-open-data.s3.amazonaws.com/photos/214908530/large.jpg

The alea subgroup have the two bands close together & in the lower part may meet or touch, obliterating the intervening space.

[Psyche]

The alea subgroup comprise five species in Singapore.
They are .A. sublustris, milleri, normani, phanda & aroa.

The subgrop is very difficult to ID.
Most features are variable & may be subjective.
The observations below is based on valid examples in C&P4, Fleming, Otsuka & Yutaka.

Two species are probably extinct in Singapore.

A. phanda is idetifiable by the HW spots 6 & 7 forming a column.
https://singapore.biodiversity.online/species/A-Arth-Hexa-Lepidoptera-000442

Arhopala aroa.
This has the bands narrow so the markings are well-spaced.
The HW spot 6 tapers markedly from top to bottom becoming more triangular.
https://thaibutterflies.com/wp-content/uploads/2016/07/Arhopala-aroa-1.jpg
Sunny actually shot one in which the HW spot 6 was almost triangular.
This picture seem to be lost.

[Psyche]

The other three members of the alea subgroup are probably still extant but separating them apart is problematic.
Features are not absolute & overlap.

28321


Arhopala sublustris..
By far the commonest species.
FW with spot 9 shifted slightly inwards.
FW postdiscal band often partially dislocated at vein 4.
HW spot 6 tapers from top to bottom (ie decrease in width downwards.)variable, usually without overlap, but sometimes with small overlap on the cellend bar.
Upperside male bright reflective blue.
Upperside female FW brown border along termen usually not taper to tornus.
Valid examples.
https://www.inaturalist.org/observations/86282154
https://www.inaturalist.org/observations/86168391
https://www.inaturalist.org/observations/163447208
https://www.inaturalist.org/observations/86165404
https://www.inaturalist.org/observations/69087182

Set specimen as Arhopala ralanda ridleyi then. (Taxion ralanda falls as a junior synonym to sublustris .)
https://singapore.biodiversity.online/species/A-Arth-Hexa-Lepidoptera-000443
Female. Note marginal brown border uniform width.
https://www.inaturalist.org/observations/89216268


Arhopala milleri.
FW with spot 9 in line with the postdiscal band.
HW with spot 6 tapers from top to bottom (as in sublustris.) but usually spot broad.
Male upperside more matt (less reflective) indigo blue.
Female upperside FW marginal brown border always taper to tornus.
The observations below are suggestive without confirmations.
1. FW spot 9 in line;HW spot 6 broad. Bukit Timah 2021
https://inaturalist-open-data.s3.amazonaws.com/photos/138107696/large.jpeg
2.FW spot 9 in line;Hw spot 6 with only a little overlap with the cellend bar.
https://inaturalist-open-data.s3.amazonaws.com/photos/207941759/large.jpg
Addendum
There appear to be one valid example of A. milleri
These two images are of the same individual.
https://www.inaturalist.org/observations/7978402
https://www.inaturalist.org/observations/7978401
The upperside is of a less reflective darker indigo blue.
https://www.surforma.com/en/decor/indigo-blue-l3546/
Compare with A. sublustris brighter blue in flash.
https://inaturalist-open-data.s3.amazonaws.com/photos/141899787/original.jpeg
https://www.inaturalist.org/observations/163447208
The colour also match Fleming's L211A Plate 92 of A. mulleri.


Arhopala normani.
FW spot 9 near inner edge or shifted in as in sublustris.
HW spot 6 hardly tapers, widely overlapping the cellend bar.
Note this is the only Singapore Arhopala stated as such in C&P4.
Male upperside deeper blue than sublustris.
Female with marginal brown border of uniform width to tornus.

Central Water catchment Area 2019. Note HW spot 6 is broad & widely overlapping the cellend bar.
https://inaturalist-open-data.s3.amazonaws.com/photos/207941834/large.jpg

The specimen in BOS can't be A. normani as the HW spot does not overlap the cellend bar.
The upperside is dark & FW spot 9 is in line.
Probable A. milleri with narrow markings.
https://singapore.biodiversity.online/species/A-Arth-Hexa-Lepidoptera-000439


TL Seow: Cheers.