Prince George's County executive-elect Parris Glendening announced yesterday that he would recommend Richard Castaldi, a newly elected County Council member from Greenbelt, as the county's representative to the Metro Board.

If approved by the County Council as expected, Castaldi, 38, will replace defeated councilman David Hartlove. Glendening's decision to replace Hartlove comes two weeks after the Metro Board, in an effort to end one of the county's most bitter community disputes, voted to uphold the Green Line metro route ending near the Rosecroft Raceway, instead of a route that would end a few miles north, near Branch Avenue. Proponents of the Branch Avenue line angrily accused the outspoken Hartlove of acting improperly since he had already become a lame duck.

Hartlove said yesterday that he would like to have continued in his post, but Glendening said he believed an elected official could best represent the county's interests. Castaldi has remained neutral in the Green Line dispute.

The Castaldi announcement came yesterday amid a flurry of political activity as the new executive and council prepared for their inauguration Monday, while their predecessors stripped their offices of files and mementoes.

Council members polled yesterday said they will support Frank Casula as chairman and Floyd Wilson as vice chairman, both of whom are beginning their third terms on the council. Casula, who ran on a council ticket with Glendening in 1974 and 1978, is expected to act as a bridge between the council and the executive, as well as a liaison between the five new members of council and the four incumbents.

Following his press conference, his fourth since his landslide victory a month ago, Glendening also put the finishing touches on an hour-long speech for his inauguration ceremony, received a stream of visitors, and said that he will announce the names of his first four departmental appointees on Tuesday.

In making those replacements, Glendening, a Democrat, is attempting to distance himself from the previous Republican administration of County Executive Lawrence J. Hogan, informed sources said. The department heads who will be replaced, according to sources, are Barbara Anderson, head of the Office of Aging; James Trexler, director of Central Services; Charles Deegan, acting director of the Office of Licenses and Permits, and Burton Oliver, director of the Office of Program Planning and Economic Development. All are Republican appointees of Hogan. Anderson is the chairwoman of the county's Republican Central Committee, the policy-making body of the local party.

"These people were appointed solely for political reasons," said a high-level Glendening associate. "It's just that we want professionals in there. These stand as the worst examples of what we're trying to change."

During his campaign, Glendening repeatedly charged that Hogan had appointed political associates, instead of qualified professionals, to high positions. Yesterday Hogan shrugged off the criticism saying the department heads "are political appointments."

In announcing his choice of Castaldi for the Metro Board, Glendening pointed out that Castaldi has served nine years on the Council of Government's Transportation Planning Board, including a term on the COG Board of Directors.

Another person in jeopardy of losing his job has been council administrator Samuel Wynkoop, who was deputy county commissioner under former county executive Winfield Kelly. But Casula said yesterday that a majority of the council did not wish to change administrators without a qualifed replacement in the middle of what is expected to be a difficult first year.