Abstract. We show that the non-arithmetic lattices in PO(n, 1) of Belolipetsky and Thomson [BT11], obtained as fundamental groups of closed hyperbolic manifolds with short systole, are quasi-arithmetic in the sense of Vinberg, and, by contrast, the well-known non-arithmetic lattices of Gromov and PiatetskiShapiro are not quasi-arithmetic. A corollary of this is that there are, for all n 2, non-arithmetic lattices in PO(n, 1) that are not commensurable with the Gromov-Piatetski-Shapiro lattices.