For his last record, 2013’s Nomad, Tuareg musician Bombino teamed up with Black Keys’ Dan Auerbach, finding common ground in the overlap of his western guitar-influenced desert blues and Auerbach’s rootsy southern rock. This time, his choice of collaborator seems more intriguing; Dave Longstreth, of Brooklyn art rockers Dirty Projectors, has a reputation for framing African pop influences in unexpected ways. But the results are less surprising than you might imagine. Longstreth keeps a low profile, and though there is plenty to enjoy in Bombino’s propulsive guitar work and the slow unfolding of meditative tracks such as Igmayagh Dum, there’s also the faint sense of an opportunity missed.