PSS computed at ω/f = 3.1 for a rotation Ω / Ω_K = 0.38 and four gravito-inertial rays in the physical space belonging to the three different types of phase-space structures: a surviving KAM torus (blue), a period-5 island chain (green/light green), and a chaotic zone (red). The light green ray on the middle panel is the stable periodic orbit at the centre of the period-5 island chain. The period of an island chain is defined as the number of corresponding structures on the PSS (see Sect. 4.3.2). These rays cross the PSS on points of corresponding colours. On all figures showing rays in the physical space, the limits of the domain of propagation given by Γ(ω) = 0 are drawn in magenta.