Skipper ID

[Silverstreak]

Hi Seow,

Your assistance will be much appreciated.

I have been looking at this skipper for the last 3 hours , the more I look at it the more confused I get!!!

It is as large as a Erionota thrax thrax (Banana Skipper), what bothers me is the forewing white ,it is a rather pristine specimen and looks exactly the same on the other side , so it is unlikely due to wear and tear leading to the white on the forewing leading edge. Further there were another 2-3 similar looking specimens with this white fore wing edge encountered. This is the only one I managed a few shots on.

It is unlikely to be a Erionota hiraca apicalis ( White Tip Skipper) as the white is not at the apex, there is no purplish wash on the hind wings , further the antennae is white only at the bottom, the top is brown.




Apologies for the quality of the shot , it was taken in extreme shade at ISO2000 1/13sec at F/6.3 Handheld.

[Psyche]

After comparing with your shot of E. hiraca apicalis here, I have to say that your pic is the same species.
http://www.butterflycircle.com/check...wbutterfly/252

On the forewing the pale area along the costa to the apex matches, as well as the position of the darker patch and the dark "spots" within the pale area.

On the hindwing all the dark patches also matched.

The antennal club is 2/3 white and 1/3 black. the black being along the medial lower side.
I have always find it difficult to corelate the antennal colour as it depends on how they are held, and probably the effect of the flash.

TL Seow

[Silverstreak]

Thanks Dr. Seow !

We will have to take note that the fore wing white region does not necessarily restrict to the apex.


Cheers!

[Psyche]

I have done some rechecking on this skipper as I thought there was something odd about it.

Its great you spotted all those differences, ie the larger size, the distribution of the white patch on the wingtip, the less white on the antennae, though I am not sure about the purple wash.

So I went round checking the Erionata species, and I realised the pattern of E. thrax is actually quite similar if not for the lesser amount of white and less dark patches.
I realised these could be variable.
Here are examples of E. thrax.
http://www.butterflycircle.com/check...wbutterfly/253 Pic 2 & 3 only.
http://www.rainbowlodgecambodia.com/...20Skipper).htm
Here is an example of E. torus.
http://www.google.co.uk/imgres?q=%22...w=1280&bih=488
The other differences between thrax & hiraca are
1. the subapical black marks tend to be spots in thrax and smudges in hiraca.
2. the pale area within the dark patches on the hindwing is of roughly even width in thrax and irregular & narrowed at the top in hiraca.

From these two plus your other observations means that this skipper is actually Erionata thrax.

TL Seow

[Silverstreak]

Thanks Seow, much appreciated!

These 2 additional observations are discernible and of great help in differentiating the E. thrax and E. hiraca.

The other differences between thrax & hiraca are
1. the subapical black marks tend to be spots in thrax and smudges in hiraca.
2. the pale area within the dark patches on the hindwing is of roughly even width in thrax and irregular & narrowed at the top in hiraca.

Cheers!

[Psyche]

The bit about the the subapical markings in E. thrax being spot-like is rather inconsistent and perhaps best ignored.

The key features in the ID of E. hiraca should be:
1. The antennal club is entirely white above.
2. The central pale area on the hindwing beneath is narrowed in the upper portion.
3. The apical part of the forewing underside white from costa to termen margin. (may apply to the male only.).

A word of caution with criterion 3. The text in C&P4 states "The female appears to be separable from E. thrax only by its smaller size.
The male of hiraca have on the upperside the distal half of the apex whitened. This is mirrored on the underside, thus rendering the whole tip white.(Not just the costal half.)
The female have no white on the upperside, and so by logical extension will have no white on the distal half of the apex on the underside. This will make the female practically identical to E. thrax on the forewing underside.

Criterion 2 appears to be the most consistent and useful.
I have not seen a female hiraca for verification and would really appreciate if anyone have a pic of it

TL Seow