Growing up in Los Angeles, Matthew Caughthran became a fan of punk bands like the Ramones and Black Flag at the same time that he was exposed to Mexican music in the predominantly Latino suburb of Pico Rivera.

Caughthran, 32, now fronts Mariachi el Bronx, which he describes as the "alter ego" of his punk rock band, the Bronx. The group's songs feature witty, ironic and romantic lyrics written mostly in English and performed with traditional mariachi brass, wind, string and percussion arrangements.

The act's self-titled second album was released Aug. 2 by ATO Records, the label co-founded by Dave Matthews, and landed the band a coveted appearance on NBC's "The Tonight Show With Jay Leno" on Aug. 3. The CD contains 12 songs including the banda-inspired "Norteño Lights," the romantic "Revolution Girls" and the self-referential "Mariachi el Bronx," a ballad featuring the all-female band Mariachi Reyna de los Angeles.

Mariachi el Bronx's unique mixing of musical styles stemmed from a 2006 appearance on Fuel TV's "The Daily Habit," when the show unexpectedly asked the Bronx to perform an acoustic number. In response, the band came up with a mariachi arrangement of its song "Dirty Leaves."

"It was awesome," Caughthran says, "the start of an epic adventure that is now five years deep."

Interested in exploring this punk-mariachi hybrid further, Caughthran called his longtime friend Vincent Hidalgo, with whom he wound up writing songs in the same vein.

Thus was born Mariachi el Bronx. Even as the Bronx continued to perform and record, the same members, including Hidalgo, began playing mariachi gigs under their new name. Their 2009 debut album?self-titled, like their new album, and released on Swami Records in the United States?has sold 9,000 units, according to Nielsen SoundScan.

"It's a little hard to call it mariachi," acknowledges Hidalgo, the son of Los Lobos' David Hidalgo, "because it's in English and a lot of the chord changes are rock'n'roll-based and come from a punk background."

Mariachi el Bronx will open for Foo Fighters on nearly two dozen U.S. dates starting Sept. 14 in St. Paul, Minn. The tour continues until the end of October, with a final show on Oct. 20 in Sacramento, Calif., and a few concerts in Canada. The group is also performing at several festivals including the Austin City Limits Music Festival on Sept. 18.

"When you're doing something out of the box, the most important thing is to be honest with the music," Caughthran says. "We really respect both cultures and genres, and I think that comes across."