During the AACM’s late-60s heyday it was a given that musicians like Muhal Richard Abrams, Roscoe Mitchell, and Anthony Braxton would look far outside the jazz continuum for ideas. But of all its vaunted alumni, reedist and composer Henry Threadgill has displayed the most voracious stylistic appetite and the most profound skills as a synthesist–nothing ever seems outside his reach. Since the early 90s the rigor and complexity of Threadgill’s writing has often been upstaged by his bands’ unusual instrumentation, and his latest project, Zooid, won’t likely change that: the group mixes tuba (a holdover from his Very Very Circus), cello (a key presence in his influential Sextett), nylon-stringed guitar, oud, drums, and his own astrigent alto saxophone and probing flute. On Zooid’s sole album, Up Popped the Two Lips (2001)–a live vinyl-only release is slated for next year–his compositions are more serpentine than ever, with constantly shifting meters and instrumental combinations. The songs are rich in rhythmic and harmonic alterations , and Threadgill sets up improvised gambits that force the players to be intensely alert, yet the music remains accessible. This is the band’s Chicago debut, and Threadgill’s first headlining gig here since 1995. Fri 12/17, 8 PM, HotHouse, 31 E. Balbo, 312-362-9707, $30. See also Saturday.