This is the rarely-seen Strymon istapa clenchi, which I chanced upon while hiking Cactus Spring Trail on March 21, 2014.
Showing a bit of the dorsal side. I'm not sure what is going on with the pale spot on the wing, and it flew off before I could see the left wing.
Same trail, next year: April 5, 2015. Just saw one on this day. This one oviposited on Apricot Mallow buds.