zathura preferred to mupdf

.config/ranger/rifle.conf

@@ -161,6 +161,7 @@ ext pdf, has okular,   X, flag f = okular -- "$@"
 ext pdf, has epdfview, X, flag f = epdfview -- "$@"
 ext pdf, has qpdfview, X, flag f = qpdfview "$@"
 
+ext epub, has zathura,  X, flag f = zathura -- "$@"
 ext epub, has mupdf, X, flag f = mupdf "$@"