Arianespace Inc., the marketing arm of the French rocket-launching firm, has appointed Diana H. Josephson director of marketing. Josephson formerly headed Space America Inc., the Bethesda startup company that was among three finalists in the bid to acquire the Commerce Department's Landsat operations.

John C. Parker, president of Microbiological Associates in Bethesda, has been named chief executive officer of the organization's parent firm, Santa Clara, Calif.-based Daryl Laboratories. Parker, who will retain his responsibilities as president of the Bethesda firm, will be based here.

Evaluation Research Corp. has elected Ray Mahr president of the Vienna firm's engineering subsidiary, Analytic Disciplines Inc. He replaces Cliff Rigsbee, who has left the firm. Mahr was director of ADI's underseas science and technology group.

Federal Engineering Inc., a communications engineering firm, announced that Ronald F. Bosco and Philip J. Freedenberg have joined the Gaithersburg firm as president and vice president, respectively. Both Bosco and Freedenberg were formerly vice presidents at M/A-Com Inc.

The accounting firm of Snyder, Newrath & Co. has promoted Donna M. Thompson to manager and Paula M. White to senior accountant. Thompson, who joined the firm in 1983 as a management consultant, will direct the firm's move into the property management and hospitality areas. White, formerly a staff accountant, will supervise staff accountants.

Thomas P. Genis has been appointed marketing director for and a principal in the Kostecky Group, an engineering and architectural firm. Genis will be responsible for broadening the company's marketing efforts in Pennsylvania, the District, Maryland and Virginia.

Ryan Advisors Inc., a Gaithersburg health-planning firm, has appointed Greg Van Pelt executive vice president, Anne Ryan senior vice president and William Mallari vice president for planning.

Ricardo E. Sese and William F. Taylor have been named vice presidents of the Washington architectural and engineering firm of Mills, Clagett and Wening.

Federline Mechanical, a mechanical contracting firm based in Gaithersburg, has named James D. Lafley vice president of commercial operations. A graduate of Virginia Polytechnic Institute, Lafley was vice president of Warner Mechanical Corp.

TeleSec Temporary Services has promoted Cordelia Galligan to branch manager of its Falls Church office, and Ann Latham to District customer representative.

Ram Leather Care in Arlington has named William S. Schaffer, formerly general manager, vice president of operations.