The killing of Hernan Cruz, 52, brings to 43 the number of media workers slain in Honduras since 2003, the spokesman said.
Cruz was discovered shot to death inside a taxi in Santa Rosa de Copan, 450 km west of Honduras's caital Tegucigalpa.
The victim, who owned several taxis, hosted a news and opinion programme on a radio station in San Juan de Opoa, where he once served as a justice of peace.
Carlos Mejia, a 31-year-old executive at Radio Progreso, was stabbed to death last month inside his home in the northern province of Yoro.
Ninety percent of murders of journalists in Honduras go unpunished, Human Rights Commissioner Roberto Herrera Caceres said last week.
His office has information on nearly 100 other cases where journalists have been attacked or threatened with death, Herrera said.
Honduras, with 90.4 homicides per 100,000 people, is the most violent country in the world. The global median homicide rate in 2012 was 6.2 per 100,000 people.