I made a mistake on the identification of this photo when this post was first published. I called it a Western Pygmy-Blue, Brephidium exilis which was incorrect. The correct identification of this butterfly is the Ceraunus Blue, Hemiargus ceraunus (linked to my gallery where I have others). And you can see others’ photos from throughout Central America and the southern half of the United States on butterfliesandmoths.
¡Pura Vida!