Propertius was, of course, the first thing I looked at. To me, it just didn't match. That's why I sent it in. It seemed much closer to E. horatius. In the Audubon butterfly field guide, 1981 (yes!), plates 267 and 270 place good pictures of propertius and horatius side by side facilitating comparison. Compare them with the image above and I will rest my case. Are the images in the guide IDed correctly?

I will leave it to the experts, but I have a slightly uneasy feeling that perhaps a higher value was placed here on where the critter was found and a somewhat lesser weight on what it looks like. The fact of the matter is that I am very much not an expert.

http://butterfliesofamerica.com/imagehtmls/Pyrginae/Erynnis_propertius_F_Paiute_Mt__Kern_Co_CA_USA_2-VI-07_119_i.htm
Guides usually have limited examples and many species have variations as well as subspecies differences. Duskywings (Erynnis) are a variable genus and are often difficult to ID. Location along with phenotype are important in getting a correct identification. When I started butterfly identification, I also questioned location for some species but experience as well as BG expert guidance showed that this was an essential tool in identification. There are numerous images in "BugGuide" and "Butterflies of America" which can be referenced which are very helpful to me.

lacks the prominent white triangles on the upper FW. Juvenalis has them, but this one lacks the 2 white dashes inboard of the triangles on juvenalis, among other differences.