Chlosyne gabbii gabbii
Before the development of much of southern California near the coast, this butterfly was much more common. When the Emmels published The Butterflies of southern California in 1973, it still flew in the dunes west of LAX. Now, this is very much a butterfly of the mountains along the coast from below Monterey south into northern Baja. The lack of dots along the hind wing submarginal area easily separates it from the mylitta crescent, a similar-sized butterfly it is sometimes confused with. Distinguishing it from palla can be tough at times except that palla's southern limit is probably within the Sierra Nevada range around Lake Isabella, well inland from gabbii populations. Recent DNA testing* has actually suggested that gabbii is more closely related to acastus than it is to palla.
* Zhang J., Cong Q., Shen J., Song L., Opler P.A., Grishin N.V. 2023. "Additional taxonomic refinements suggested by genomic analysis of butterflies." Taxonomic Report of the International Lepidoptera Survey 11(1). doi:10.5281/zenodo.7604053.