From a media release (which can be found HERE), the regional airline stated that:
"Regional Express (Rex) will commence 3 return flights each weekday between Cairns and Townsville from this Monday, 6 July 2015. Rex will be adding some 60,000 annual seats to the route with 34 weekly flights."
Their services are as follows (table from Media Release):
Rex Saab 340B VH-ZRZ operated the first flight from Townsville (YBTL) as ZL5418.
It then operated the return service to Townsville (YBTL) as ZL5419.
Rex Saab 340B