Many rejoiced and few mourned in Central America today as news spread that deposed Nicaraguan dictator Anastasia Somoza had been assassinated in Paraguay. But the killing may yet cause serious aftershocks in Nicaragua and the entire region.

No definite links have been shown between Somoza's assassins and the revolutionary government in Managua that ousted him 14 months ago to the day. But even suspicion that the Sandinista regime was involved could jeopardize much-needed support from the United States.

It took most of a year for the Carter administration to push a $75 million aid package for Nicaragua past conservatives in Congress. Final approval came only after the White House declared that Nicaragua's government is not found to be supporting violence or terrorism outside its borders.

A diplomat reached by telephone in Managua voiced concern that now "there will be a lot of questions raised" that could make the Carter administration's support for Nicaragua and for changes in neighboring countries all the more difficult to carry out.

"It will depend on what information finally emerges about the assassination," said the diplomat. "We'll have to wait and see."

The Nicaraguan government is nevertheless exultant over Somoza's murder. A day of rejoicing was announced. Government leaders toured neighborhoods that had been the target of bombings on Somoza's orders. The state radio station likened the assassination to the killing of Somoza's father in 1956, considered a heroic act by the current rulers.

"We are Christians, but in all sincerity we cannot hide our happiness that a genius of evil has died," Rafael Cordova Rivas, a member of the five-man Nicaraguan junta, told reporters in Managua. He accused Somoza of ordering the deaths of as many as 50,000 of his people.

Cordova Rivas said in a recent tour of Latin America that "Nicaragua will not be free until Somoza is killed." He stated this morning, however, that the Sandinistas "had nothing to do directly with the death of Somoza," and speculated that the assassins might even have been Paraguayan revolutionaries who wanted to end "the stain" brought on their territory by the dictator's presence.

Some reports indicate the assassins come from the ranks of Argentine Montonero revolutionaries who may have Sandinista connections. The head of the Montoneros, Mario Firmenich, is known to have visited Managua several times since the revolution.

There was apparently no shortage of people who wanted Somoza dead, however.

Even ex-members of Somoza's once fiercely loyal National Guard have bitterly denounced the dictator for deserting them, and some observers speculated that Somoza's love life may have earned him deadly enemies.

Somoza was once regarded as the most powerful and influential right-wing ruler in Central America, at least in part because of his ability to curry the favor of the United States. But by the time he was deposed, even some of his most conservative allies were relieved to see him go.

Somoza's ouster in the face of both a massive leftist-led popular insurrection and intense pressure from the U.S. government that once supported him was looked on as an omen by conservatives in nearby El Salvador, Guatemala and Honduras. But the fall of the man himself was not lamented. For the rightists of the area, his regime was a symobl of anticommunism at any cost. While they might favor the stance, he was never their hero.

Some suggest that if he had not been so intent on maintaining his personal dynasty, and thus the focus for popular discontent, the area might have been saved the trauma of a revolutionary regime in its midst.

"A lot of people thought he should not have stayed so long in power," said one conservative Guatemalan businessman this morning. "He should have left several years earlier. No one considered the possibility of his ever coming back."

The Sandinistas nevertheless used the threat of Somoza's return and of "counterrevlution" linked to him as constant themes in their rhetorical attempts to maintain the spirit of the insurrection during the trying period of reconstruction.

There are frequent reports in the Managua press of armed confrontations between government troops and Somoza's former National Guardsmen. Only last week an alleged plot was uncovered to assassinate the nine members of the powerful Sandinista National Directorate.

But even the alleged leader of that plot was reported in the local press as saying the only reason he would want to bring Somoza back to Nicaragua would be to do away with him.

"Somoza was almost universally despised," said a U.S. diplomate in El Salvador.

Is speculation that the Sandinistas were involved in Somoza's killing increases, however -- and it is already rampant -- the dictator's ghost may do more to damage the revolution than he could have hoped.

"It is a pretty rare case when anyone gains from an assassination," said a U.S. official in Managua. "What the Sandinistas will gain or lose by Somoza's death is still an open question."