M. Lamar Muse, the former president of the highly successful Southwest Airlines, is getting back into the airline business after a 2 1/2-year absence.

Muse and his son Michael recently-announced formation of Muse Air Corp., which will do business as MuseAir, a major short-haul, low-fare airline serving the eastern half of the nation. Muse Air Corp. asked the Civil Aeronautics Board for the authority to start service initially from Houston on six routes, to St. Louis, Memphis, Tulsa, Dallas/Fort Worth, San Antonio and Corpus Chrisit. Future plans include service to a total of 24 cities from points in Texas east, with Houston, Chicago and Atlanta serving as major hubs. Washington was not included in the 24 cities named.

"This seems to be a good time to start a new airline, particularly short-haul in mid-America," the elder Muse said in a telephone interview. With deregulation, many of the major airlines have reduced frequencies and raised their fares on the short-haul markets, he said. "A great opportunity has opened up for a specialist in that kind of market."

That is the kind of market Muse tapped as president of Southwest from 1971 until the spring of 1978, presiding over its phenominal growth as an intra-Texas airline specializing in low-fare, frequent, on-time, commuter-type, turn-around air service. Muse lost control of the airline in March 1978, his contract was bought out and he signed an agreement that he wouldn't compete with Southwest, until at least October 1980.

That time is now up, and Muse is very optimistic about the new airline. The trend of the airline industry in the 1980s appears to be specialization, he thinks, with the major airlines -- with large airplanes -- staking out the long-haul routes, leaving the shorter routes to others. "We're going to fill that void hopefully," he said. "That's where the money is going to be made in the '80s -- attracting the passengers now going shorter distances by interstate highway and private automobile. There's a great market to tap."

Muse said the new airline hopes to start service next spring or summer with six of seven 85-passenger DC9 Series 10 aircraft. The company has already placed deposits on five DC9 Super 80 aircraft and options for five more from McDonnell Douglas Corp. with deliveries starting in 1983. The Super 80s carry up to 172 passengers and are considered the most fuel-efficient and quiet airplanes in their class.

In the CAB filing, the elder Muse is listed as chairman of the board and chief executive officer and Michael Muse is listed as president, chief operating officer and treasurer. The company said it will open with a capital base of at least $32 million. Muse said the money has not been raised yet but there have been expressions of interest which he declined to detail.