Found within an hour of dusk in a desert canyon not far from the Colorado River. I first noticed it fluttering around, and then landing on, the flower of Mirabilis laevis var. villosa (formerly Mirabilis bigelovii) seen in the photo above.

From studying the 1991 paper by Powell(1), I'm convinced this is Lithariapteryx jubarella. In particular, the orange tranverse band (near distal 1/3 of forewings); the two large ("gem"-like) bumps on each inner edge of the forewings (rather than one, as in L. abroniaeela); the gray hindwing distal fringe; and the Mirabilis association...together all point to L. jubarella over L. abroniaeela.