...might be better for now. I doubt it is the species C. femorata, as it doesn't exhibit the reddish highlights on the elytral apices and sharply angled posterior elytral margins characteristic of that species. Also C. femorata is more often associated with non-oak hardwoods (maple, apple, sycamore, ash, etc.). Other species in the group such as C. rugosiceps, C. viridiceps, C. misella, and some of the undescribed species are usually associated with oak.