KCRW’s Global Beat: Mexico recently highlighted emerging artists from the Gulf state of Veracruz, which included music from Vico Diaz, a master of the leona, the guitar-shaped, four-stringed fretted instrument that acts like a bass, played in that region. A composer and explorer of traditional Mexican music who seeks out elusive new sounds, Diaz brings us a tropical, jazzy “Sapo,” or “frog,” replete with the instrument of Chiapas, the marimba.