akeys=[1,2,3]
avals=['North-Apulia','Calabria','South-Apulia']
amap={e[0]:e[1] for e in zip(akeys,avals)}
ax=scatter_by(dfsouthns, 'palmitic', 'palmitoleic', by='area', labeler=amap, mfunc=make_rug, mms=20)
ax.grid(False)
ax.legend(loc='upper right');