Helfer, How to Know the Grasshoppers, gives a key for M. rhombifolium vs. M. retinerve. He says that M. rhomb. has a spur, or something like that, projecting from the front edge of the pronotum. Likewise, he says that M. retinerve has a straight-edged front edge of the pronotum. Have you seen this feature? I wonder if the key is reliable--all the Microcentrum I've seen--not many--have a straight edge on the pronotum.

Patrick Coin
Durham, North Carolina

Patrick, I didn't notice anything like that in the field. Certainly in the photo (the other one shows it better) the front of the pronotum looks smooth. Does the spur look pretty obvious in the picture in the book?

--Stephen

Stephen Cresswell
Buckhannon, WV
www.stephencresswell.com

There is no diagram in that reference(Helfer, How to Know the Grasshoppers)--just a description in a dichotomous key. There are lots of illustrations in that reference--they just didn't do that one. There's an illustration of the whole body of a Microcentrum species, for instance. Perhaps the reference's key is wrong, or perhaps the character is not obvious. I can't find any photos on the web of this character, either. Singing Insects of North America has photos:
M. retinerve--whole insect and detail of pronotum
M. rhomb.--just the body, pronotum not visible! Maybe I can just make out a little nub on that photo. The coloration sure looks like your photo, green with mottled white marks. I'll upload one of mine, it looks to be a much plainer green withouth the mottling. Who knows?

Hey, I'm happy to know the genus--I just thought I was going to be able to distinguish the species--the key looked very easy.

Patrick Coin
Durham, North Carolina

Wow, less than five minutes after posting! Thanks very much, Eric.

--Stephen

Stephen Cresswell
Buckhannon, WV
www.stephencresswell.com