Martincito's picture

A pulchrina or jota?

Observed: 28th August 2012 By: MartincitoMartincito’s reputation in InvertebratesMartincito’s reputation in InvertebratesMartincito’s reputation in InvertebratesMartincito’s reputation in Invertebrates
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Description:
Identifications
Species interactions

No interactions present.

Species with which Silver Y (Autographa gamma) interacts

Comments

Martin Harvey's picture

Y oh Y?

Thanks Douglas, you make a very good point there, I certainly didn't look closely enough at it!

Not trying to make excuses for myself, but I know that I've been caught out like this before when faced with the question "is it species X or Y" and failing to realise that it's actually species A! The human mind is easily misled (or at least mine is anyway).

Having said all that it does seem to be a particularly richly coloured Silver Y, so not surprised that it caught some of us out to start with.

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Entomologist and biological recorder

Donald Hobern's picture

Autographa nightmares

Thanks, Douglas and Martin. What specifically about the 'Y' mark drives you to gamma? I must admit I've never been very happy with identifying any of this broad group of Plusiinae. It always seems that every single character is variable across all species and that the identification from external characters always requires a Bayesian approach. The triangular checking in the fringe on this moth does seem something that better fits gamma than pulchrina, but what else? Best wishes, Donald

Donald Hobern

Douglas's picture

gamma

Yes; very richly coloured; can see why it was a little misleading.

Flight time should be your biggest clue; the two suggested species shouldn't be flying now. (there are very occasional records from out of the published flight time though, so this shouldn't never be relied on - although these may be mis-identifications, as this one was!)

Also those two rarely have a joined 'Y' - a feature constant on gamma. There are rare individuals of pulchrina and jota with a complete 'Y' but in those cases it is a different shape.

There are subtle differences in the markings and also the colour isn't quite right for the two originally suggested.

This site is very good for a wide range of images showing the variation and is always very reliable:
http://www.lepiforum.de/cgi-bin/lepiwiki.pl?Autographa_Gamma

http://www.lepiforum.de/cgi-bin/lepiwiki.pl?Autographa_Pulchrina

Best wishes,

Douglas
www.douglasboyes.co.uk
Twitter: @diarsia

Donald Hobern's picture

Thanks

Thanks, Douglas.

I appreciate the pointers. Can you characterise how the 'Y' shapes differ on those pulchrina where it is complete? I don't for example see much difference between these two on Lepiforum (first from the page for pulchrina, second from gamma):

http://www.lepiforum.de/webbbs/images/f1_2007/pic50170.jpg
http://www.lepiforum.de/webbbs/images/f1_2010/pic61612.jpg

I'm just back in Europe after several years in Australia where the local Plusiinae drove me crazy. I suspect that some of those I identified there as Chrysodeixis subsidens may have been Chrysodeixis eriosoma. The key distinction stated between these species is the same complete/broken 'Y' issue but collections show significant variation. Here is one with a break only on one side:

http://www.flickr.com/photos/dhobern/3205225345/

Best wishes,

Donald

Donald Hobern

Martincito's picture

Thanks to everyone for yet

Thanks to everyone for yet another iSpot tutorial. The wing colour fooled me, not knowing that it isn't a reliable identifier. I also spent some time studying this page: http://www.northumberlandmoths.org.uk/files/idtips/2442-beautiful-golden.... The moth has now made its get-away from the ivy, so has escaped the indignity of having its genitals examined, not that I'd have a clue as to how to go about that indelicate task!

Martin Harvey's picture

Y shapes

Donald raises soem interesting questions about the variability of the Y, which as he shows can sometimes be solidly joined in Beautiful Golden Y (BGY). Having looked again at the photos above following Douglas's initial prompting, my opinion remains that Silver Y (SY) is the most likely solution, due to:
- the Y can be joined in BGY but this is uncommon
- the post-median line is a bit more smooth/rounded in BGY, more jagged in SY
- BGY has a slightly more pointed wing-tip (apex) than SY (difficult to judge from the angle of these photos but it looks more like SY to me)
- the dark shading between the Y and the wing shoulder is less extensive in SY than it is in BGY
- SY has narrower dark shading along the sub-terminal line than BGY does, shown in the 5th photo above
- Flight period is perhaps a clue as well, although BGY flight period does run through August further north in Britain (I saw several in north Wales last week).

I'll admit that all these reasons can be subject to variation, and that Donald is right to highlight the variability and difficulty of this group of species. All I can say is that having looked at it properly I think the balance of evidence leads to Silver Y. But without dissecting the specimen there will always be room for argument.

Good to see this moth - makes me wonder how many times I've muddled them in the past, will keep a closer eye on them now!

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Entomologist and biological recorder