HST images with contours of the CO or [CI] total-flux maps from ALMA for the 23 ALPAKA galaxies with HST observations. The lowest white contour is a “pseudo-contour” – see Appendix B in Roman-Oliveira et al. (2023) for details – at 4 RMS. The additional yellow contour in the ID8 panel shows a second source detected in CO(2–1) (see Sect. 6.4 for details). The CO transitions and HST filters shown here are listed in Tables 2 and 3, respectively. The white bar in the bottom left of each panel shows a scale of 1″.