What are the morphological characteristics of the black gill beetle?

The adult beetle is 17 ~ 22mm in length, showing a long and narrow oval shape. The body is dim and covered with black or dark brown fluff. The widest chest backboard is located in the middle of the side, and the front edge has long brown hair edges, which are distributed in rows. The front corner is blunt and arc-shaped, the back corner is straight, the top end is sharp, and the rear edge is without edges. Coleoptera is slender, with 4 longitudinal edges on each side inconspicuous.