Except for his early professional years with the British Honduras Broadcasting Service, a colonial subsidiary of the BBC, Mario Valdes has spent most of his career with WGBH, the PBS affiliate in Boston where he specialized in African American history and the African Diaspora. An “emeritus” staffer for “Say Brother” / “Basic Black,” the nation’s first and longest running television series produced for and by the black community, he has also worked with PBS Frontline and is a research contributor for the Image of the Black in Western Art project at Harvard.