The radio core luminosity against the median of the isophote shape parameter of the bulge inside R_e (B₄) and average bulge ellipticity within R_e both derived after excluding the most-PSF affected data points inside . Downward arrows denote upper limits for undetected sources. Boxy and discy isophotes have B₄ < 0 and B₄ > 0, respectively. Core-Sérsic galaxies (enclosed in boxes) show a tendency to possess brighter radio core luminosities, they are also systematically rounder (see Sect. 4.4). However, only 7/20 (35%) of our core-Sérsic galaxies are radio-loud. Radio-loud galaxies are enclosed in orange diamonds. In the left panel, the red-dashed line separates boxy and discy galaxies, whereas in the right panel such lines are shown to demarcate the location of core-Sérsic galaxies. Nuclear radio emission is more prevalent in round, boxy sources than in flat, discy ones. A representative error bar is shown at the bottom of each panel.