It is on page 8-47 of owners' manual.
If you don't have one, you may go to
mazdausa.com to register as an owner with VIN, and download it.
By looking at it now, there isn't one fuse specifically for the side markers.
However, there are some fuses seem to be related
(it says : for protection of various circuits
such as: 6, 10, 12. Also 29/Hazard warning flahsers)
(under the hood - not the fuses behind the glove compartment)