chi(c0)(3915) as the lightest c(c)over-bars(s)over-bar state

The state χc0(3915) has recently been demoted by the Particle Data Group from its previous status as the conventional cc¯ 23P0 state, largely due to the absence of expected DD¯ decays. We propose that χc0(3915) is actually the lightest cc¯ss¯ state, and calculate the spectrum of such states using the diquark model, identifying many of the observed charmoniumlike states that lack open-charm decay modes as cc¯ss¯. Among other results, we argue that Y(4140) is a JPC=1++ cc¯ss¯ state that has been not been seen in two-photon fusion largely as a consequence of the Landau-Yang theorem.