Grasshopper ID, please. - Chortophaga viridifasciata

Moved

Moved from Southern Green-Striped Grasshopper.

… David J. Ferguson, 1 July, 2012 - 2:12pm

There is an interesting paper

here that outlines most of the differences, though it is biased somewhat. The insects they were looking at in the study were all from Nebraska and Iowa, with no "true" southern australior included. However, I do tend to agree with the conclusions reached in this paper.

In short though, C. australior is usually more strongly patterned, darker on the sternum, with dark bars across the hind femora (? always present on the lower margin). The dark patterning is least developed in green form individuals, and some individuals may be as "plain" as is usual in "typical" viridifasciata. Southern australior also have the pronotum usually shorter (less produced with a more obtuse angle to the rear), and the median crest averages lower. It usually appears slightly sockier, but I've never measured parts, it may just be that the wings average shorter, or it could be that the whole insect is a bit more "compact". In typical form, the two seem quite distinct, but problems come when it turns out that not one of the distinguishing characteristics is stable as you move north to south; southward all traits become more like "typical" australior, but not equally at the same rate of change, and not equally the same at different seasons.

… David J. Ferguson, 25 October, 2011 - 11:39am

Wow ...

... some geographic selection on-going, I'm sure. I've printed Brust, Hoback and Wright (2008) - will read it later today. A Chortophaga-ist dedicated to a few years of travel and collection across the allegedly-two species' ranges could resolve the problem or go blind in the effort. Some biological process is ongoing, selection, evolution, speciation ... Chortophaga has some big chromosomes worthy of analysis as I recall from my cell-biology days.

… William Donald Newton, 25 October, 2011 - 12:08pm

In my collection they are all C. viridifasciata,

but they are separated here on BugGuide, following Daniel Otte and the Orthoptera Specis File (which most authors do at the moment), so I'm going to put your photos here under the australior category. In the future this may get adjusted back to subspecies on BugGuide, but not for the moment.

Moved from ID Request.

… David J. Ferguson, 25 October, 2011 - 10:50am

indeed she is Chortophaga

Something of a judgement call as to the best name - I'd go with C. australior I think but Chemblee may be inland enough to be in an area where they are intermediate with C. viridifasciata. Drawing a line between the two "species" is somewhat arbitrary.

… David J. Ferguson, 22 October, 2011 - 10:33pm

C. australior reported from Marietta, GA ...

... just NW of Chamblee:

http://bugguide.net/node/view/69316

I'll go with C. viridifasciata or whichever has priority.

Thanks.

… William Donald Newton, 23 October, 2011 - 6:33am

When combined as one species (which has been done)

C. viridifasciata is the name of priority, and australior becomes the subspecies or synonym of the other. Currently the trend is to call them different species, but biologically they certainly are not (at least not the way I see it - two distinct species should not be blending into one another where they meet). They are not exactly the same though, and most authors at least give australior subspecies status. Yours "looks" more like australior to me, but I'd need to see more from the same population to be sure if she is "good" pure australior or if you are in the blend zone in that area.

… David J. Ferguson, 25 October, 2011 - 10:46am

What nuance of anatomy ...

... separates the allegedly two species? This is some good biology! I'll keep looking for them, for sure!

… William Donald Newton, 25 October, 2011 - 11:23am

Chortophaga ...

... perhaps?

… William Donald Newton, 20 October, 2011 - 11:50pm