What do "LC/P" and "PTD" stand for in reference to airport communications?
LC/P: Local control, primary frequency, from LC, local control, which is a usual control position in the tower.

"The Local Controller is primarily responsible for separating and providing safety alerts to aircraft in the airspace surrounding the airport and aircraft on the active runways" (source)


Source

PTD: As @Riccati commented, it means Pilot to Dispatcher, according to the Airport / Facility Directory Legend.

Airlines are required by regulation to provide direct communication means for aircrew.


Aircraft dispatcher training (source)


See also: Can airline pilots communicate with dispatchers?