To determine the size of the insect use the grid on the sheet, which is sew in 5mm grid.
Found in a Black Widow web. Third picture is of the last two right antennomeres.
Found underneath a slab of bark, about 3/4 inch in length, elevation about 700ft
I corrected the location. I saw several (20 plus) of these beetles while hiking along the OC&E Trail. They would flush and fly away when I approached from about 5 feet away. Not nearby any alkali habitat.