A seating assembly including a base having a bottom ring supported by casters, a pan supported by the bottom ring, a central hub forming an upwardly opening cavity, a plurality of legs extending outward and downward from the central hub to the bottom ring, a one-piece molded seat shell, a mounting bracket forming four apertures and including a female connector and at least one rib member that extends downward adjacent the female connector, the at least one rib member including end edges that forms first and second stop surfaces, the mounting bracket attached to the bottom of the seat by passing fasteners through the apertures, a support arm, a mounting assembly including, a cup member, a base tube, an annular mounting collar and a pivot cover forming an upwardly opening annular channel and an inverted U-shaped opening, the pivot cover attached to the mounting collar with the first end of the support arm extending through the inverted U-shaped opening and the at least one rib member received within the annular channel.