Rep. Stephen F. Lynch yesterday clobbered William M. Bulger Jr. in their bruising state Senate race, relegating the Bulger legacy to the history books and opening a new chapter for South Boston.

Leading a powerful campaign army still in fighting shape from his 1994 legislative race, Lynch scored a stunning Democratic primary victory over the namesake son of the former Senate president.

Lynch swept the diverse 1st Suffolk District, but it was South Boston that delivered the killing blow to Bulger, refusing by a resounding 20-point margin to transfer power from father to son.