David Ungerer, co-founder and formerly president of Reston Publishing Co., has been named president and chief operating officer of the Taft Group, a Washington information services and publishing firm. J. Richard Taft, formerly president, will become chairman and chief executive of the firm, which he founded in 1969. At Taft, Ungerer will direct the company's expansion into software, telemarketing and training, according to a company statement.

Cathleen P. Black, publisher of USA Today, has assumed the additional responsibility of executive vice president for marketing at Gannett Co. Inc., a new position at the paper's parent company. Black, formerly publisher of New York magazine and assistant publisher of Ms. magazine before she joined USA Today in 1983, will supervise all of the company's national advertising and sales promotion activities.

Richard E. Lyng, deputy secretary of Agriculture from 1981 until this January and president of Lyng and Lesher Inc., an agricultural advisory firm, has joined the Washington public and government relations firm of Gray & Co. as a member of its agriculture communications group advisory board. Gray & Co. also appointed Mary C. Foerster, formerly Philadelphia's deputy director of commerce, and Diana Aldridge, a former account executive at Gray and aide to Sens. Floyd Haskell (D-Colo.) and Edward M. Kennedy (D-Mass.), to vice presidents.

Burson-Marsteller has appointed J. Thomas Koutsoumpas, formerly an aide to Sen. Edward M. Kennedy (D-Mass.), as a government relations counselor and Susan E. Ridge, formerly legislative assistant to the Ohio Senate Republican Caucus, to account representative in the public relations firm's Washington office.

Matthew MacWilliams, formerly deputy national field director for the Mondale for President campaign, has been named senior associate at Greer & Associates, a Washington advertising and media firm.

Levine & Rudd Inc., a Washington public relations firm, has appointed Pamela Kerwin vice president for marketing and communications. She was previously a national marketing manager for Control Data Corp.

MIICORP, a marketing consulting firm based at Dulles International Airport, has named J. Christopher Hapner director of public relations. Hapner was formerly public relations manager at Martin Marietta Data Systems in Greenbelt and news media relations manager at Alcan Aluminum Corp. in Cleveland.