De-wrapped abundance distribution of HCG 91c. Each spaxel in the datacube was reprojected in the azimuth-distance plane according to its location with respect to the galaxy center. For spaxels associated to a given aperture but without a reliable individual measure of 12 +log (O/H), the aperture-derived value of 12 +log (O/H) is shown instead. Spiral arms can be identified and tracked from 2 kpc outwards in this de-projected space. The iso-distance ellipses shown in the different panels of Figs. 7 and 8 become horizontal lines in this projection. Inclined purple lines mark the boundaries of spiral structures displaying a rapid variation of the oxygen abundance. The star-forming complexes found by Vogt et al. (2015) to have discrepant oxygen abundances with respect to their immediate surroundings are marked with white circles.