KANSAS CITY, Mo. (AP) _ Jurors in a Las Vegas casino skimming trial heard hours of tapes Tuesday in which reputed underworld figures talked about the dangers of an extortion plot allegedly concocted by a mobster against Gov.-elect Robert List of Nevada in 1978.

Nick Civella, who authorities say was the mob's chief in Kansas City until his death in 1983, worried in the wiretapped conversations that Frank Rosenthal, allegedly the mob's representative in Argent Corp., would ''snitch'' and ''open up a whole can of worms'' during investigations into the alleged plot against List.

Civella was worried that List would ''out of spite'' kill a deal in which Argent Corp. owner Allen Glick had reached tentative agreement to sell his casino holdings to Fred Doumani and Edward Doumani.

The tapes, made at a Kansas City law firm in November 1978, were heard during the trial of eight alleged organized crime figures charged with conspiring to gain hidden control of Argent Corp. and with skimming $1.2 million in gambling proceeds from casinos it owned.

Glick, who is not charged, was present for his fifth day of questioning by the government. He purchased Argent with $62.75 million loaned from the Teamsters union Central States Pension Fund.

The government contends organized crime figures in Chicago, Kansas City and Milwaukee used their influence over pension fund trustees to obtain the loan, and then muscled in on Glick by forcing him to hire Rosenthal in a key position.

The alleged extortion plot came in 1978 as the Nevada Gaming Commission was attempting to ban Rosenthal from Las Vegas casinos, Glick testified.

In a tape made Nov. 13 at a Kansas City law firm, Civella, Peter Tamburello and Carl DeLuna talked about stories in Las Vegas newspapers in which Rosenthal was accused of trying to blackmail List by threatening to have an unfavorable story printed about him unless he stopped the gaming commission from banning Rosenthal.

Joseph V. Agosto, whom the government contends was the Kansas City mob's contact in Las Vegas, had told DeLuna that he was concerned about what statements Rosenthal would make as the gaming commission and federal authorities investigated the extortion plot.

Civella worried about whether he should talk ''to the people up north,'' in an apparent reference to crime figures in Chicago, and ask them to talk to Rosenthal.

DeLuna said he didn't think the situation was as serious as Agosto felt, and that Rosenthal would not do anything to hurt ''La familias in total.''

Civella said in a Nov. 14 conversation with DeLuna that he had talked to Rosenthal himself and that Rosenthal said he had actually killed the newspaper story.

DeLuna replied that Rosenthal probably had lied because that was a ''180- degree turn'' from what he had heard from Agosto.