Fusing traditional sounds from the northern and southern halves of Madagascar, “Mampamangy,” by the quartet Loko Gasy, is a superb reminder of how good music from that richly cultural island can be.

Fusing traditional sounds from the northern and southern halves of Madagascar, “Mampamangy,” by the quartet Loko Gasy, is a superb reminder of how good music from that richly cultural island can be.