Tuesday, 13 July 2010

Burnished Brass Pellon / Halifax

Northowram this year
Manor Heath this year




Burnished Brass last night.






Burnished Brass 2004 Pellon. Are these both races and are they being split.





2 comments:

AndyC said...

This is taken from the yorkshire yahoo group,thanks C.Fletcher
"It is almost 50 years since the suggestion was first made that an additional
species may be present within the taxon Diachrysia chrysitis. More recently is
has been shown that the moth that had been referred to in Europe as ssp tutti is
in fact a sibling species of D. chrysitis, the western representative of the
eastern species D. stenochyrsis. The English name Cryptic Brass has been
suggested for this species. Following a long investigation, the two species have
been definitively distinguished by their morphology, differences in structure of
the wings scales, electrophoresis and different male pheromones. So far as it is
known, the two species have a similar distribution in Europe, including Britain"

"In the field, separation is based on whether the brown, non-metallic median
fascia is complete (chrysitis) or interrupted by a band of green scales, these
thus forming an "H" shape (stenochrysis). Examples at each end of the spectrum
may be safely named using this character, however intermediate examples exist
where the median fascia is traversed by a very narrow line of green scales.
These will probably require examination of genitalic characters to be certain of
the species. However a character that appears to be fairly constant is that in
stenochrysis, the upper end of the lower section of the brown median fascia is
distinctly rounded. In specimens of chrysitis where the median fascia is
interrupted by a narrow line of green scales, this lower section tends to be
square-ended."

Colin Plant wrote an article in End Rec (122: 128-135) which filled out a lot
more detail and made it seem a lot more complicated than Harry's summary. He
says at the end that although more work needed to be done, it seemed that:

1. Moths with two widely separated vertical green bars are true chrysitis.
2. Moths with these two bands joined clearly and distinctly to create a green
H have been referred to as f. juncta
3. Moths referable to f. juncta are regarded by some authors as a separate
species called Diachyrisia tutti.
4. Examples of tutti inwhich the cross bar of the H is at least 3mm wide may
be referable to the Eastern Palaearctic species D. stenochrysis.
5. Intermediate forms in which the cross-bar of the H is poorly defined also
exist.

Other noctuid "splits" in the past have made some entomologists wary, for
example with Silver Y and Angle Shades which were proven to be incorrect and a
bit of a taxonomic blunder, but this split seems to be supported by those that
know about these things. The best parallels being the Gold Spot/Lempke's split.
It is likely that stenochrysis/chrysitis represent parallel evolution following
which the two species have expanded their range to the extent that they are now
overlapped.

AndyC said...

1. intermediate
2..chrysitis
2 pics - ?intermediate (does it have a thin patch of green scales or is this an illusion?)
2 pics - stenochrysis
Thanks to Charlie Fletcher for this.... so please record accordingly if any doubt record as intermediate.