The elytral tubercles are more prominent than those on my specimens of Z. granicollis ssp. ventriosus (central and northern Tulare County). Also the tip of the elytra is more pronounced in this specimen. So I would say it isn't ventriosus, but I don't know what it is. This area of the southern Sierra Nevadas is interesting, having afinities with both the Sierras, the Mojave Desert, and the mountains of southern California.

Perhaps its the nominative ssp., Z. g. granicollis. They have a good collection of this at LA County NHM.
Update - After looking at the specimens at the LA NHM, I'm still not sure. The elytral tubercles don't look quite as coarse as in Z. g. granicollis, but closer to Z. uteanus including the luster (distribution? - there was only one specimen of uteanus at the museum, from Mt. Charleston, Clark County, NV. Aside from other NV, and UT locations, it has also been found in CA's Granite Mountains.)
Still, without the actual specimen, or a more detailed photo, I think its best to leave this at genus level.

I collected another Zopherus granicollis over the weekend and ran it through key reviewed the information again. After all that I've come to the conclusion that your specimen is indeed Z. granicollis ventriosus. I think the angle of your shot made the tubercles appear more prominent.