Hasora chromus & vitta

[Commander]

Dr Seow, I have these two recorded in my archives as H. chromus. Can you please help to validate?

25744

25745

[Commander]

And these as H. vitta

25746

25747

25748

25749

[Psyche]

These two species have puzzled & confused me for years.


According to Eliot's key in C&P4.

Hasora vitta
1. UpF with a subapical spot 6.
2. HW band at least 2 mm broad.
3. HW basal area glazed bluish green.
4. Male UpF without a brand.


Hasora chromus.
1. UpF without a subapical spot 6.
2. HW band narrow 1 mm wide.
3. HW basal area bluish purple.
4. Male UpF with a divided brand.

These are clearly seen in Yukata.
http://yutaka.it-n.jp/hes/90210001.html
http://yutaka.it-n.jp/hes/90250001.html


Based on these Post 1 & 2 are all Hasora vitta.

H. chromus is quite confusing.
Some regions in India & Australia have the band rather broad.
The FW subapical spot 6 may be present & vestigial on the underside but absent on the upperside.
http://lepidoptera.butterflyhouse.com.au/hesp/chromus.html


I suspect in Singapore some esamples are hybrids between the two, in particular post 1 pic 2 which looks like H. chromus but keyed out as H. vitta.


TL Seow; Cheers.

[Commander]

Thanks, Dr Seow. Now this makes it even more confusing than before. The individual in Post 1, Pic 2 is the same individual that appears in the opening image on Horace's life history article - http://butterflycircle.blogspot.com/2010/10/life-history-of-common-banded-awl.html

Horace also wrote that "Below, both sexes are pale purplish brown. On the hindwing, there is a prominent and narrow white to bluish white discal band partitioning the wing into an inner and an outer half. The inner edge of the band is more sharply defined compared to the outer edge. In contrast, the discal band on the forewing is faint and extends only over the upper portion of the wing. The female has two apical spots in spaces 6 and 7 of the forewing with the one in space 7 absent from some specimens."

The photo of that individual eclosed from a pupa that Horace bred in that batch of ​Hasora chromus caterpillars. I took it that it was a female from the early records of the caterpillar that was bred. So that Post 1 Pic 2 is quite certainly a H. chromus as it was bred from an egg.

[Psyche]

Since Post 1 pic 2 is proven to be Hasora chromus some adjustment is needed to the key in separating them.
I had make another observation but with so many conflicting IDs on the web had thought it not reliable, but now it looks very reliable.

The HW white marginal line is short to about vein 3 in H. vitta.
In H.chromus the HW white marginal line extends less prominently to the apex.

The two may be separated thus.

Hasora vitta;
1. Male without a brand.
2. FW almost always with a subapical spot 6.
3. HW band broad about 2mm.
4. HW basal area bluish grey /green.
5. HW marginal white line at tornus short to vein 3.

Hasora chromus.
1. Male with a FW brand.
2. FW typically without a subapical spot 6 in the male ; in female may be present (sometimes wit spot 7).
3. HW band narrow about 1mm. but occasionally broader.
4. HW basal area dull bluish purple.
5. HW white marginal line extend less distinctly to near apex.

TL Seow: Cheers.

[Commander]

Thanks, Dr Seow. The last key #5 seems to be quite consistent in several of the shots that I have. Very useful!

Here are a couple more field shots by Horace that also show the marginal line.

25759

25760

[Psyche]

There will always be problem with worn individuals or variants where the line fades away faster, but combined with the UnH dull purple sheen will made the ID very reliable.


TL Seow: Cheers.