Silvery checkerspot

Chlosyne nycteis should have white spots on the hindwing. So yours is probably another one.
http://bugguide.net/node/view/302602
http://bugguide.net/node/view/171253
Yours is a Phyciodes sp., but these are all very similar, I do not have the time to check and you have to look very carefully to the markings and spots.
My first sight guess (!) would the Phyciodes tharos and Phyciodes cocyta. The problem with these 2 species is, that even for experts it is not always easy to separate them see the link here:
http://bugguide.net/node/view/462350/bgp...
Tharos:
http://bugguide.net/node/view/411/bgpage...
Cocyta:
http://bugguide.net/node/view/25729/bgpa...
I am sure, that other people will get closer, maybe also due to the geographical range.