Euchloe hyantis hyantis
'California' Pearly Marble
The hyantis/lotta group of butterflies is a difficult group, and it doesn't help that every population is a little different (acc. to Paul Opler, Western Butterflies, who has studied this group extensively). There may be three or more species involved (possibly with three species in the San Bernardinos alone - andrewsi, lotta, and hyantis?), with some gene flow apparent among them. Ken Davenport has written that both hyantis and lotta fly at Bald Mountain, where my photograph was taken; that the population of hyantis there is heavily marbled; that field marks don't hold true for these butterflies on the Kern Plateau (the thickness of the forewing black bar, for instance); and he mentions "intermediacy" between many individuals in the two species. When I visited Bald Mountain on June 28, 2017, this was just one day before Ken's latest date for any lotta in California, while hyantis may fly well into July.