We construct left invariant quaternionic contact (qc) structures on Liegroups with zero and non-zero torsion and with non-vanishing quaternioniccontact conformal curvature tensor, thus showing the existence of non-flatquaternionic contact manifolds. We prove that the product of the real line witha seven dimensional manifold, equipped with a certain qc structure, has aquaternionic Kaehler metric as well as a metric with holonomy contained inSpin(7). As a consequence we determine explicit quaternionic Kaehler metricsand Spin(7)-holonomy metrics which seem to be new. Moreover, we give explicitnon-compact eight dimensional almost quaternion hermitian manifolds with eithera closed fundamental four form or fundamental two forms defining a differentialideal that are not quaternionic Kaehler.
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