Euchloe hyantis lotta
'Desert' Pearly Marble
For now, the desert subspecies (or species, depending on whom you ask) of the hyantis group best fits here. The literature on this complex of butterflies is kind of a mess. We are probably dealing with at least a couple of species. As an example, E. hyantis andrewsi flies in June along the highway near Lake Arrowhead in the San Bernardino Mountains. It is known to be distinctive and possibly imperiled. Not far from there, another "Pearly Marble" is quite common on the east side of Big Bear Lake. It also appears that the desert lotta differs from hyantis, and both Ken Davenport and Jim Brock "have both noted that hyantis and lotta both occur together along the Chimney Peak Road and in the Kennedy Meadows area on the Kern Plateau" (Emmel update, p.58). The limited DNA testing on Euchloe* provided some clarity, with the authors "asserting that biological and phenotypic characters indicate that species-level isolation has been attained for E. hyantis, E. lotta Beutenmüller, 1898 and E. andrewsi Martin, 1936, respectively" despite "no or little sequence divergences for members of the Euchloe hyantis complex." That is limited to mtDNA/COI analysis.
*Werner Back, Michael A. Miller, and Paul A. Opler "Genetic, Phenetic, and Distributional Relationships of Nearctic Euchloe (Pieridae, Pierinae, Anthocharidini)," The Journal of the Lepidopterists' Society 65(1), 1-14, (1 March 2011).