Her death, in a hospital, was announced on Facebook by the band’s drummer, Don Bolles, and confirmed by her cousin Beth Bergman, who said the cause was cancer.

Ryan would stand calmly onstage with her bass lines propelling the music along with Bolles’ beat, while Germs’ leader, Darby Crash, delivered the songs with anarchic, often bloodily self-mutilating intensity: confronting audience members, lighting matches, smashing glasses on his head. Germs shows often sparked riots in the audience.

The band made one album and lasted until 1980, when Darby Crash (born Jan Paul Beahm) killed himself with a heroin overdose. He had often spoken of a five-year plan to create a notorious cult band, record one album and then kill himself to make himself legendary.

Germs formed in 1976 with an initial lineup of Darby Crash, Lorna Doom, Pat Smear (born Georg Albert Ruthenberg) on guitar (he later toured with Nirvana and became a member of Foo Fighters) and Belinda Carlisle on drums (she was replaced by Bolles).

Carlisle, who went on to be the lead singer of the Go-Go’s, wrote on Twitter on Thursday that Ryan “was a visionary and a trailblazer” who “never compromised.”

Teresa Marie Ryan was born Jan. 4, 1958, in Dallas and grew up in Southern California and Nebraska. Her father, James Patrick Ryan, was a lumber store manager; her mother, Betty Marie (Bruenecke) Ryan, was a homemaker.

Ryan and Carlisle, who were high school friends, were recruited into Germs through an ad placed by the other two original members calling for “two untalented girls” to join a band. Darby Crash renamed them — Carlisle became Dottie Danger — and, true to early punk style, musical skill didn’t matter. Ryan learned her instrument while in the band, although she earned praise from musicians like Mike Watt, bassist for the Minutemen, who said on Twitter, “Good people, I love LOVE germs bass lines!”

Germs played its first show in April 1977, and six months later released the single “Forming"/"Sexboy,” which is often cited as the first Los Angeles punk record.

Germs became a resident band at Los Angeles club the Masque and thrived on shock value. At some shows, Darby Crash would cut into his chest a symbol that he called “circle one”; Germs fans showed loyalty by giving one another cigarette burns. Laura Jane Grace of the band Against Me! posted on Twitter, “I can still see the ‘Germs burn’ on my wrist from when I was 14 years old.”

Germs’ only album, “(GI),” was produced by Joan Jett and released in 1979. Its lyric sheet revealed the poetic intelligence of the words that Darby Crash would drunkenly yowl, slur or skip during performances. The band also recorded six songs for the William Friedkin film “Cruising,” although only one, “Lion’s Share,” was used.

During the late-1970s punk era, Germs shows grew tumultuous. “It all got terribly violent and extremely frightening towards the end,” Ryan told The Guardian in 2008. “There was this influx of punks from Southern California who latched on to our gigs and basically made it impossible for us to play without a riot happening. That was the beginning of the end.”

By 1980, most promoters were unwilling to book the band. “Now we can’t play anywhere,” Darby Crash complained in Penelope Spheeris’ 1981 punk documentary, “The Decline of Western Civilization.” He started another band, but regrouped Germs for a final show Dec. 3, 1980. Four days later, he was dead.

Ryan moved to New York City with her boyfriend, who was the bassist in Jett’s band, the Blackhearts. Born Gary Moss, he took Ryan’s last name as a stage name when he joined the band in 1979, performing as Gary Ryan. They were married in the early 1980s and divorced in the 1990s.

Teresa Ryan is survived by her brother, Richard Ryan.

In New York City, Ryan worked for art galleries. She returned to California in the early 2000s to help care for her ailing father, and worked there as a personal assistant and a bookkeeper. She lived in Agoura Hills, California.

Ryan was an adviser for “What We Do Is Secret,” a 2007 movie about Germs that featured Shane West as Darby Crash and Bijou Phillips as Lorna Doom. After singing with the reunited Germs at a party for the film, West went on to tour as lead singer with the surviving band members. In clubs, and on Warped Tour in 2006 and 2008, Germs performed for a younger, more well-behaved generation of punk fans.

“It was totally surprising to get the band together again,” Ryan told The Guardian, “but it’s also the most comfortable thing in the world.”.