for the speedy ID.
Actually, I goofed. I shouldn't neglect the things 'in the back of my mind'; I submitted a similar bee in 2005 from upslope of this location (Mt. Pinos summit): 1.

so for species ID it would be helpful to note flowers present in the vicinity

It would also be helpful to know the habitat and the exact size of the bee

The relevant revision is by Rozen (1958)

on which above bee was feeding, flowers in bloom include: a couple of Asteraceae (Chaenactis glabriuscula, C. santolinoides); Lupinus excubitus; Penstemon centranthifolius; Phacelia douglasii, P. egena; all in Pinyon-juniper woodland within about 200ft radius. At least five days later (just notice, they were out on May 18 already)) we can add: a small Mimulus (johnstonii); a Camissonia sp.; Eriophyllum pringlei; Linanthus aureus; Yucca whipplei.

I arrived at the size (8mm, given above) by measuring the diameter of the flower the bee was feeding on. I'd give it no more than 8.5mm.

Your comments are always appreciated, so thanks!