Those already familiar with the music of percussionist Mongo Santamaria won't need much prompting to hear him this weekend: mere mention of his infectious Afro-Cuban jazz and roots music acts like a magnet for the previously indoctrinated. Among the uninitiated, the jazz fans can think of him as not only a splendid conga drummer but also a salsa version of Art Blakey: like Blakey, Santamaria's bands have served as proving grounds for to-be-famous jazz players such as Chick Corea, Hubert Laws, and saxist Justo Almario. The less savvy may recognize his name only from the passing reference in Mel Brooks's Blazing Saddles--when the brute named Mongo punches out a horse, a Mexican bystander cries, "It's Mongo! Santa Maria!"--but even that's a good enough reason to catch a bona fide legend helming an irresistible band. Tonight through Sunday, Joe Segal's Jazz Showcase, Blackstone Hotel, 636 S. Michigan; 427-4300.