The Aggies are the fourth program to boycott against the Spartans this season ... after it was claimed in a lawsuit, filed by former college swimmer Riley Gaines, that a member of the SJSU roster is a biological male.

Gaines notably competed against transgender swimmer Lia Thomas at the NCAA championships in 2022 ... and has since become an activist against trans women competing in women's sports.

Per the lawsuit filed in September, Spartans player Brooke Slusser roomed with the SJSU athlete on several occasions in 2023 ... before the teammate disclosed to her she considered herself to be a "transgender woman" in April 2024.

The suit also claimed the SJSU team feared for its safety in practice due to the player's "80 MPH" spikes ... "which was faster than she had ever seen a woman hit a volleyball."

After these details were released, several schools decided to back out of their contests against SJSU ... the first being Southern Utah University in September. Boise State then canceled its Sept. 28 game and Wyoming opted out of its upcoming Oct. 5 match.

Utah State -- scheduled to go up against SJSU on Oct. 23 -- was the latest.

Utah Governor Spencer Cox backed the Thunderbirds and Aggies shortly after the news broke ... saying, "I stand with the students, coaches and leadership at @SUUtbirds and @USUAggies in their decision to forgo their women’s volleyball matches against San Jose State."

"It is essential that we preserve a space for women to compete fairly and safely. Our female athletes are left grappling with this difficult issue because the NCAA has failed in its responsibility to protect female athletes and women’s sports."

"It’s time for the NCAA to take this seriously and protect our female student-athletes."

Wyoming's Governor Mark Gordon also supported the Cowgirls' decision, saying "It is important we stand for integrity and fairness in female athletics."

As for SJSU, the school said the program is in compliance with both the NCAA and Mountain West Conference rules and regulations.