I’m posting photos of an additional specimen to complement the single picture in BG. I’m including views of the antennae, which in my mind, are the most eye-catching feature, and the one that caused me to recognize this as something different.

Based upon the geographic range listed American Beetles, this would be Ginglymocladus discoidea VanDyke. I have another from Nevada County that should be G. luteicollis Van Dyke based upon geographic range, but the morphological differences between the two are pretty subtle. The photo of G. luteicollis in BG does not allow comparison. I will post this other specimen separately.

EDIT: I found that I had taken a picture of it when alive; I'm adding that now.